diff --git a/client/src/adapter/__tests__/manaSourceSelectionWireTypes.test.ts b/client/src/adapter/__tests__/manaSourceSelectionWireTypes.test.ts
index 09741924d1..18bd28f042 100644
--- a/client/src/adapter/__tests__/manaSourceSelectionWireTypes.test.ts
+++ b/client/src/adapter/__tests__/manaSourceSelectionWireTypes.test.ts
@@ -59,6 +59,7 @@ describe("mana-source selection wire types", () => {
           source: { object_id: 17, incarnation: 3 },
           ability_index: 0,
           mana_type: "Blue",
+          output: { type: "Concrete", data: "Blue" },
           atomic_combination: null,
           restrictions,
           penalty: "None",
diff --git a/client/src/adapter/generated/interaction/index.ts b/client/src/adapter/generated/interaction/index.ts
index 0e71b51b46..fff6e5b18f 100644
--- a/client/src/adapter/generated/interaction/index.ts
+++ b/client/src/adapter/generated/interaction/index.ts
@@ -57,7 +57,7 @@ export type SelectionConstraint = { "type": "count", "data": { min: number, max:
 
 export type ConfirmSemantics = "immediate" | "explicit";
 
-export type InteractionActionCode = "passPriority" | "chooseMeldPair" | "chooseEntryAttackTarget" | "playLand" | "castSpell" | "foretell" | "activateAbility" | "declareAttackers" | "declareBlockers" | "chooseUntap" | "chooseExert" | "chooseEnlist" | "chooseClashOpponent" | "chooseZoneOpponentChooser" | "choosePileOpponent" | "chooseAnnouncingOpponent" | "chooseGiftRecipient" | "chooseAssistPlayer" | "commitAssistPayment" | "mulliganDecision" | "reorderHand" | "tapLandForMana" | "untapLandForMana" | "spendPoolMana" | "unspendPoolMana" | "selectCards" | "chooseRemoveCounterCostDistribution" | "selectCoinFlips" | "chooseOutsideGameCards" | "selectTargets" | "chooseTarget" | "chooseReplacement" | "orderTriggers" | "cancelCast" | "equip" | "crewVehicle" | "activateStation" | "saddleMount" | "transform" | "playFaceDown" | "turnFaceUp" | "submitSideboard" | "choosePlayDraw" | "chooseOption" | "submitVoteCandidate" | "submitSpellbookDraft" | "submitPilePartition" | "choosePile" | "chooseBranch" | "submitLifeRedistribution" | "chooseDamageSource" | "selectModes" | "decideOptionalCost" | "chooseAdventureFace" | "chooseModalFace" | "chooseAlternativeCast" | "chooseCastingVariant" | "keepAllCopyTargets" | "choosePermanentTypeSlot" | "activateNinjutsu" | "castSpellAsSneak" | "castSpellAsWebSlinging" | "castSpellForFree" | "castSpellAsMiracle" | "castSpellAsMadness" | "decideOptionalEffect" | "respondToSpliceOffer" | "decideOptionalEffectAndRemember" | "payUnlessCost" | "chooseUnlessCostBranch" | "chooseActivationCostBranch" | "payCombatTax" | "chooseRingBearer" | "choosePair" | "chooseDungeon" | "chooseDungeonRoom" | "unlockRoomDoor" | "rollPlanarDie" | "chooseRoomDoor" | "tapForConvoke" | "harmonizeTap" | "declareCompanion" | "companionToHand" | "discoverChoice" | "graveyardPaidCastChoice" | "cascadeChoice" | "rippleChoice" | "freeCastWindowChoice" | "chooseTopOrBottom" | "chooseMutateMergeSide" | "cipherEncode" | "chooseLegend" | "chooseBattleProtector" | "setAutoPass" | "cancelAutoPass" | "setPhaseStops" | "setPriorityPassingMode" | "setPriorityYield" | "setMayTriggerAutoChoice" | "setTriggerOrderTemplate" | "assignCombatDamage" | "assignBlockerDamage" | "distributeAmong" | "chooseCounterMoveDistribution" | "chooseCountersToRemove" | "submitPayAmount" | "retargetSpell" | "learnDecision" | "selectCategoryPermanents" | "chooseKeptCreatures" | "chooseKeptPermanents" | "chooseX" | "submitPhyrexianChoices" | "chooseManaColor" | "payManaAbilityMana" | "castPreparedCopy" | "chooseSpecializeColor" | "castParadigmCopy" | "passParadigmOffer" | "grantDebugPermission" | "revokeDebugPermission" | "concede" | "declareShortcut" | "respondToShortcut" | "declineShortcut" | "precastCopyShortcut" | "endContinuousEffect" | "debug";
+export type InteractionActionCode = "passPriority" | "chooseMeldPair" | "chooseEntryAttackTarget" | "playLand" | "castSpell" | "foretell" | "activateAbility" | "declareAttackers" | "declareBlockers" | "chooseUntap" | "chooseExert" | "chooseEnlist" | "chooseClashOpponent" | "chooseZoneOpponentChooser" | "choosePileOpponent" | "chooseAnnouncingOpponent" | "chooseGiftRecipient" | "chooseAssistPlayer" | "commitAssistPayment" | "mulliganDecision" | "reorderHand" | "tapLandForMana" | "activateManaSource" | "backToManaPayment" | "untapLandForMana" | "spendPoolMana" | "unspendPoolMana" | "selectCards" | "chooseRemoveCounterCostDistribution" | "selectCoinFlips" | "chooseOutsideGameCards" | "selectTargets" | "chooseTarget" | "chooseReplacement" | "orderTriggers" | "cancelCast" | "equip" | "crewVehicle" | "activateStation" | "saddleMount" | "transform" | "playFaceDown" | "turnFaceUp" | "submitSideboard" | "choosePlayDraw" | "chooseOption" | "submitVoteCandidate" | "submitSpellbookDraft" | "submitPilePartition" | "choosePile" | "chooseBranch" | "submitLifeRedistribution" | "chooseDamageSource" | "selectModes" | "decideOptionalCost" | "chooseAdventureFace" | "chooseModalFace" | "chooseAlternativeCast" | "chooseCastingVariant" | "keepAllCopyTargets" | "choosePermanentTypeSlot" | "activateNinjutsu" | "castSpellAsSneak" | "castSpellAsWebSlinging" | "castSpellForFree" | "castSpellAsMiracle" | "castSpellAsMadness" | "decideOptionalEffect" | "respondToSpliceOffer" | "decideOptionalEffectAndRemember" | "payUnlessCost" | "chooseUnlessCostBranch" | "chooseActivationCostBranch" | "payCombatTax" | "chooseRingBearer" | "choosePair" | "chooseDungeon" | "chooseDungeonRoom" | "unlockRoomDoor" | "rollPlanarDie" | "chooseRoomDoor" | "tapForConvoke" | "harmonizeTap" | "declareCompanion" | "companionToHand" | "discoverChoice" | "graveyardPaidCastChoice" | "cascadeChoice" | "rippleChoice" | "freeCastWindowChoice" | "chooseTopOrBottom" | "chooseMutateMergeSide" | "cipherEncode" | "chooseLegend" | "chooseBattleProtector" | "setAutoPass" | "cancelAutoPass" | "setPhaseStops" | "setPriorityPassingMode" | "setPriorityYield" | "setMayTriggerAutoChoice" | "setTriggerOrderTemplate" | "assignCombatDamage" | "assignBlockerDamage" | "distributeAmong" | "chooseCounterMoveDistribution" | "chooseCountersToRemove" | "submitPayAmount" | "retargetSpell" | "learnDecision" | "selectCategoryPermanents" | "chooseKeptCreatures" | "chooseKeptPermanents" | "chooseX" | "submitPhyrexianChoices" | "chooseManaColor" | "payManaAbilityMana" | "castPreparedCopy" | "chooseSpecializeColor" | "castParadigmCopy" | "passParadigmOffer" | "grantDebugPermission" | "revokeDebugPermission" | "concede" | "declareShortcut" | "respondToShortcut" | "declineShortcut" | "precastCopyShortcut" | "endContinuousEffect" | "debug";
 
 export type InteractionRoleCode = "source" | "candidate" | "partner" | "attackTarget" | "target" | "paymentMode" | "abilityIndex" | "attacker" | "bandCount" | "blocker" | "blocked" | "untap" | "exert" | "enlistTarget" | "enlist" | "opponent" | "assistPlayer" | "assist" | "genericMana" | "mulligan" | "serumPowder" | "handCard" | "selected" | "counterSource" | "counterType" | "amount" | "coinFlipIndex" | "sideboardIndex" | "faceUpExile" | "optionIndex" | "triggerIndex" | "crewMember" | "stationCrew" | "x" | "mainCard" | "sideboardCard" | "playFirst" | "option" | "candidateIndex" | "cardName" | "pileA" | "pile" | "modeIndex" | "pay" | "face" | "castCost" | "permanentType" | "returnCreature" | "permissionSource" | "accept" | "spliceCard" | "splice" | "choice" | "costBranch" | "costBranchIndex" | "pair" | "dungeon" | "roomIndex" | "door" | "operation" | "convokeMana" | "harmonizeCreature" | "harmonize" | "companion" | "castChoice" | "castCard" | "placement" | "mergeSide" | "encodeCreature" | "encode" | "defender" | "protector" | "assignmentMode" | "damageTarget" | "damageAmount" | "trampleDamage" | "controllerDamage" | "destination" | "discardCard" | "learn" | "category" | "kept" | "phyrexianPayment" | "manaChoice" | "count" | "manaPayment" | "producedMana" | "color" | "player" | "castingVariant" | "mode" | "modeCost" | "castingCost" | "voteOption" | "voteCandidate";
 
diff --git a/client/src/adapter/types.ts b/client/src/adapter/types.ts
index ec938837a8..ddc7c48e62 100644
--- a/client/src/adapter/types.ts
+++ b/client/src/adapter/types.ts
@@ -668,7 +668,10 @@ export interface CastingVariantChoiceOption {
   mana_cost: ManaCost;
 }
 
-export type CastPaymentMode = { type: "Auto" } | { type: "Manual" };
+export type CastPaymentMode =
+  | { type: "Auto" }
+  | { type: "AutoExceptSacrificialMana" }
+  | { type: "Manual" };
 
 export type UnlessCost =
   | { type: "Fixed"; cost: ManaCost }
@@ -1158,6 +1161,10 @@ export type ManaSourcePenalty =
   | { PaysLifeOnActivation: { fixed_amount: number | null } }
   | "Sacrifices";
 
+export type ManaSourceOutput =
+  | { type: "Concrete"; data: ManaType }
+  | { type: "DeferredColorChoice" };
+
 export type ProductionOverride =
   | { type: "SingleColor"; data: ManaType }
   | { type: "Combination"; data: ManaType[] };
@@ -1172,6 +1179,7 @@ export interface ManaSourceSelection {
   source: ObjectIncarnationRef;
   ability_index: number | null;
   mana_type: ManaType;
+  output: ManaSourceOutput;
   atomic_combination: ManaType[] | null;
   restrictions: ManaRestriction[];
   penalty: ManaSourcePenalty;
@@ -1659,6 +1667,7 @@ export type WaitingFor =
       };
     }
   | { type: "ManaPayment"; data: { player: PlayerId; convoke_mode?: ConvokeMode } }
+  | { type: "ManaSourceSelection"; data: { player: PlayerId; options: ManaSourceSelection[]; convoke_mode?: ConvokeMode } }
   | {
       type: "ChooseXValue";
       data: {
@@ -2186,6 +2195,8 @@ export type GameAction =
   | { type: "MulliganDecision"; data: { choice: MulliganChoice } }
   | { type: "ReorderHand"; data: { order: ObjectId[] } }
   | { type: "TapLandForMana"; data: { selection: ManaSourceSelection } }
+  | { type: "ActivateManaSource"; data: { selection: ManaSourceSelection } }
+  | { type: "BackToManaPayment" }
   | { type: "UntapLandForMana"; data: { object_id: ObjectId } }
   // CR 118.3a: pin / unpin a specific pool unit during manual mana payment.
   | { type: "SpendPoolMana"; data: { pip_id: number } }
@@ -2927,6 +2938,7 @@ export interface GameState {
   combat: CombatState | null;
   waiting_for: WaitingFor;
   has_pending_cast: boolean;
+  allows_cancel_cast?: boolean;
   /**
    * CR 601.2f: The locked-in pending cast (cost, ability, object) while the
    * caster is mid-cast. Present during ManaPayment / cost-choice WaitingFor
diff --git a/client/src/components/board/__tests__/PermanentCard.test.tsx b/client/src/components/board/__tests__/PermanentCard.test.tsx
index 7c8d3f6038..0da939609d 100644
--- a/client/src/components/board/__tests__/PermanentCard.test.tsx
+++ b/client/src/components/board/__tests__/PermanentCard.test.tsx
@@ -1169,6 +1169,7 @@ describe("PermanentCard", () => {
           source: { object_id: 39, incarnation: 1 },
           ability_index: null,
           mana_type: "Green",
+          output: { type: "Concrete", data: "Green" },
           atomic_combination: null,
           restrictions: [],
           penalty: "None",
diff --git a/client/src/components/mana/ManaPaymentUI.tsx b/client/src/components/mana/ManaPaymentUI.tsx
index ac9b24a55c..834eb1d0af 100644
--- a/client/src/components/mana/ManaPaymentUI.tsx
+++ b/client/src/components/mana/ManaPaymentUI.tsx
@@ -621,6 +621,69 @@ export function ManaPaymentUI() {
   );
 }
 
+/** CR 605.3b: The engine has reached a mana ability that sacrifices a
+ * permanent. It supplies every legal capability; this display layer only
+ * renders those rows and returns the selected opaque action. */
+export function ManaSourceSelectionUI() {
+  const { t } = useTranslation("game");
+  const waitingFor = useGameStore((s) => s.waitingFor);
+  const gameState = useGameStore((s) => s.gameState);
+  const dispatch = useGameStore((s) => s.dispatch);
+
+  if (waitingFor?.type !== "ManaSourceSelection") return null;
+
+  return (
+    <AnimatePresence>
+      <motion.div
+        className="fixed inset-0 z-50 flex items-end justify-center bg-black/55 p-4 sm:items-center"
+        initial={{ opacity: 0 }}
+        animate={{ opacity: 1 }}
+        exit={{ opacity: 0 }}
+      >
+        <motion.section
+          role="dialog"
+          aria-modal="true"
+          aria-label={t("manaSourceSelection.title")}
+          className="w-full max-w-md rounded-xl bg-slate-900 p-5 shadow-2xl ring-1 ring-amber-400/40"
+          initial={{ opacity: 0, y: 16 }}
+          animate={{ opacity: 1, y: 0 }}
+          exit={{ opacity: 0, y: 16 }}
+        >
+          <h2 className="text-lg font-semibold text-amber-200">{t("manaSourceSelection.title")}</h2>
+          <p className="mt-1 text-sm text-slate-300">{t("manaSourceSelection.description")}</p>
+          <div className="mt-4 space-y-2">
+            {waitingFor.data.options.map((selection, index) => {
+              const source = gameState?.objects[selection.source.object_id];
+              return (
+                <button
+                  key={`${selection.source.object_id}-${selection.ability_index ?? "basic"}-${index}`}
+                  type="button"
+                  className="flex min-h-11 w-full items-center justify-between rounded-lg bg-amber-500/10 px-3 text-left text-sm text-white ring-1 ring-amber-300/30 transition hover:bg-amber-500/20"
+                  onClick={() => dispatch({ type: "ActivateManaSource", data: { selection } })}
+                >
+                  <span>{source?.name ?? t("manaSourceSelection.unknownSource")}</span>
+                  <span className="text-xs text-amber-200">{t("manaSourceSelection.sacrifice")}</span>
+                </button>
+              );
+            })}
+          </div>
+          <button
+            type="button"
+            className={gameButtonClass({
+              tone: "slate",
+              size: "md",
+              className: "mt-4 w-full",
+            })}
+            onClick={() => dispatch({ type: "BackToManaPayment" })}
+          >
+            {t("manaSourceSelection.back")}
+          </button>
+        </motion.section>
+      </motion.div>
+    </AnimatePresence>
+  );
+}
+
 // Color → shard symbol code for `ManaSymbol` (White→"W", …, Colorless→"C").
 const COLOR_SHARD: Record<ManaType, string> = {
   White: "W",
diff --git a/client/src/components/mana/__tests__/ManaPaymentUI.test.tsx b/client/src/components/mana/__tests__/ManaPaymentUI.test.tsx
index 2c68afa18e..639357af7c 100644
--- a/client/src/components/mana/__tests__/ManaPaymentUI.test.tsx
+++ b/client/src/components/mana/__tests__/ManaPaymentUI.test.tsx
@@ -2,7 +2,7 @@ import { act } from "react";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { cleanup, fireEvent, render, screen } from "@testing-library/react";
 
-import { ManaPaymentUI } from "../ManaPaymentUI";
+import { ManaPaymentUI, ManaSourceSelectionUI } from "../ManaPaymentUI";
 import { useGameStore } from "../../../stores/gameStore";
 import type { GameState } from "../../../adapter/types";
 import { buildGameObjectWithCoreTypes, buildObjectMap } from "../../../test/factories/gameObjectFactory.ts";
@@ -421,3 +421,63 @@ describe("ManaPaymentUI", () => {
     });
   });
 });
+
+describe("ManaSourceSelectionUI", () => {
+  beforeEach(() => {
+    useGameStore.getState().reset();
+  });
+
+  afterEach(() => {
+    cleanup();
+  });
+
+  it("dispatches only the engine-issued sacrificial source and Back action", () => {
+    const dispatch = vi.fn().mockResolvedValue([]);
+    const source = buildGameObjectWithCoreTypes(["Artifact"], {
+      id: 91,
+      card_id: 91,
+      name: "Basal Sliver",
+      zone: "Battlefield",
+    });
+    const selection = {
+      source: { object_id: 91, incarnation: 0 },
+      ability_index: 0,
+      mana_type: "Black" as const,
+      output: { type: "Concrete" as const, data: "Black" as const },
+      atomic_combination: null,
+      restrictions: [],
+      penalty: "Sacrifices" as const,
+      taps_for_mana: [],
+    };
+    const gameState = createGameState({
+      objects: buildObjectMap(source),
+      waiting_for: {
+        type: "ManaSourceSelection",
+        data: {
+          player: 0,
+          options: [selection],
+        },
+      },
+    });
+
+    act(() => {
+      useGameStore.setState({
+        gameState,
+        waitingFor: gameState.waiting_for,
+        dispatch,
+        legalActions: [],
+      });
+    });
+
+    render(<ManaSourceSelectionUI />);
+
+    fireEvent.click(screen.getByRole("button", { name: /basal sliver/i }));
+    expect(dispatch).toHaveBeenCalledWith({
+      type: "ActivateManaSource",
+      data: { selection },
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: /back to mana payment/i }));
+    expect(dispatch).toHaveBeenCalledWith({ type: "BackToManaPayment" });
+  });
+});
diff --git a/client/src/components/settings/PreferencesModal.tsx b/client/src/components/settings/PreferencesModal.tsx
index 400e761eef..89c682a38b 100644
--- a/client/src/components/settings/PreferencesModal.tsx
+++ b/client/src/components/settings/PreferencesModal.tsx
@@ -34,6 +34,7 @@ import type {
   CommandZoneDisplay,
   LogDefaultState,
   MultiplayerBoardLayout,
+  SpellPaymentMode,
   ZoneCollapseMode,
 } from "../../stores/preferencesStore.ts";
 import type { SupportedLng } from "../../i18n/resources.ts";
@@ -72,6 +73,7 @@ const CARD_SIZES: CardSizePreference[] = ["small", "medium", "large"];
 const COMMAND_ZONE_DISPLAYS: CommandZoneDisplay[] = ["auto", "inline", "compact"];
 const ZONE_COLLAPSE_MODES: ZoneCollapseMode[] = ["auto", "on", "off"];
 const CARD_PREVIEW_MODES: CardPreviewMode[] = ["follow", "side", "shift"];
+const SPELL_PAYMENT_MODES: SpellPaymentMode[] = ["auto", "autoExceptSacrificialMana", "manual"];
 const LOG_DEFAULTS: LogDefaultState[] = ["open", "closed"];
 const VFX_QUALITIES: VfxQuality[] = ["full", "reduced", "minimal"];
 const MULTIPLAYER_BOARD_LAYOUTS: MultiplayerBoardLayout[] = ["focused", "split"];
@@ -428,15 +430,12 @@ export function PreferencesModal({
                   </SettingGroup>
 
                   <SettingGroup label={t("gameplay.spellPayment")}>
-                    <label className="flex min-h-11 items-center gap-2">
-                      <input
-                        type="checkbox"
-                        checked={spellPaymentMode === "manual"}
-                        onChange={(e) => setSpellPaymentMode(e.target.checked ? "manual" : "auto")}
-                        className="accent-cyan-500"
-                      />
-                      <span className="text-sm text-slate-200">{t("gameplay.manualManaPayment")}</span>
-                    </label>
+                    <SegmentedControl
+                      options={SPELL_PAYMENT_MODES}
+                      value={spellPaymentMode}
+                      onChange={setSpellPaymentMode}
+                      renderLabel={(option) => t(`gameplay.spellPaymentOptions.${option}`)}
+                    />
                   </SettingGroup>
 
                   {isTauri() && (
@@ -723,7 +722,7 @@ export function PreferencesModal({
                           type="button"
                           onClick={handleImportTheme}
                           disabled={themeImportStatus === "loading" || !themeImportUrl.trim()}
-                          className="rounded-[14px] border border-white/10 bg-sky-600/30 px-4 py-2 text-sm text-slate-100 hover:bg-sky-600/50 disabled:opacity-50"
+                          className="rounded-[14px] border border-white/10 bg-sky-600/30 px-4 py-2 text-sm text-white hover:bg-sky-600/50 disabled:opacity-50"
                         >
                           {themeImportStatus === "loading" ? t("audioTheme.loading") : t("audioTheme.import")}
                         </button>
@@ -1537,7 +1536,7 @@ function ArtChainEditor({
             type="button"
             onClick={handleAddSet}
             disabled={!resolveSetCode(setInput)}
-            className="rounded-[14px] border border-white/10 bg-sky-600/30 px-4 py-2 text-sm text-slate-100 hover:bg-sky-600/50 disabled:opacity-50"
+            className="rounded-[14px] border border-white/10 bg-sky-600/30 px-4 py-2 text-sm text-white hover:bg-sky-600/50 disabled:opacity-50"
           >
             {t("artChain.addSet")}
           </button>
diff --git a/client/src/game/__tests__/castPaymentMode.test.ts b/client/src/game/__tests__/castPaymentMode.test.ts
index 7d9c5be5b8..f717b30312 100644
--- a/client/src/game/__tests__/castPaymentMode.test.ts
+++ b/client/src/game/__tests__/castPaymentMode.test.ts
@@ -38,4 +38,35 @@ describe("applySpellPaymentPreference", () => {
       type: "Manual",
     });
   });
+
+  it("stamps every cast-family action with the sacrificial-mana preference", () => {
+    usePreferencesStore.setState({ spellPaymentMode: "autoExceptSacrificialMana" });
+    const castTypes = [
+      "CastSpell",
+      "CastSpellForFree",
+      "CastSpellAsMiracle",
+      "CastSpellAsMadness",
+      "CastSpellAsSneak",
+      "CastSpellAsWebSlinging",
+    ] as const;
+
+    for (const type of castTypes) {
+      const action = { type, data: {} } as GameAction;
+      const result = applySpellPaymentPreference(action) as GameAction & {
+        data: { payment_mode?: unknown };
+      };
+      expect(result.data.payment_mode).toEqual({ type: "AutoExceptSacrificialMana" });
+    }
+  });
+
+  it("lets the per-game manual override dominate the sacrificial-mana preference", () => {
+    usePreferencesStore.setState({ spellPaymentMode: "autoExceptSacrificialMana" });
+    useUiStore.setState({ manualManaOverride: true });
+
+    const result = applySpellPaymentPreference(castAction);
+
+    expect((result as Extract<GameAction, { type: "CastSpell" }>).data.payment_mode).toEqual({
+      type: "Manual",
+    });
+  });
 });
diff --git a/client/src/game/castPaymentMode.ts b/client/src/game/castPaymentMode.ts
index 42ffebe37b..a94c7e6836 100644
--- a/client/src/game/castPaymentMode.ts
+++ b/client/src/game/castPaymentMode.ts
@@ -3,45 +3,52 @@ import { usePreferencesStore } from "../stores/preferencesStore";
 import { useUiStore } from "../stores/uiStore";
 
 const MANUAL_CAST_PAYMENT_MODE: CastPaymentMode = { type: "Manual" };
+const AUTO_EXCEPT_SACRIFICIAL_MANA_PAYMENT_MODE: CastPaymentMode = {
+  type: "AutoExceptSacrificialMana",
+};
 
 export function applySpellPaymentPreference(action: GameAction): GameAction {
-  // Two intended sources of truth: the durable `spellPaymentMode` preference and
-  // the ephemeral per-game `manualManaOverride` toggle. Manual wins if EITHER is on.
-  const manual =
-    usePreferencesStore.getState().spellPaymentMode === "manual" ||
-    useUiStore.getState().manualManaOverride;
-  if (!manual) return action;
+  // Manual is the per-game escape hatch and deliberately dominates the saved
+  // preference. Otherwise stamp every cast-family action with the exact engine
+  // mode so all alternate casting routes share the same payment semantics.
+  const preference = usePreferencesStore.getState().spellPaymentMode;
+  const mode = useUiStore.getState().manualManaOverride || preference === "manual"
+    ? MANUAL_CAST_PAYMENT_MODE
+    : preference === "autoExceptSacrificialMana"
+      ? AUTO_EXCEPT_SACRIFICIAL_MANA_PAYMENT_MODE
+      : null;
+  if (!mode) return action;
 
   switch (action.type) {
     case "CastSpell":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     case "CastSpellForFree":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     case "CastSpellAsMiracle":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     case "CastSpellAsMadness":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     case "CastSpellAsSneak":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     case "CastSpellAsWebSlinging":
       return {
         ...action,
-        data: { ...action.data, payment_mode: MANUAL_CAST_PAYMENT_MODE },
+        data: { ...action.data, payment_mode: mode },
       };
     default:
       return action;
diff --git a/client/src/game/controllers/aiController.ts b/client/src/game/controllers/aiController.ts
index a52f1c9eae..21e0586f62 100644
--- a/client/src/game/controllers/aiController.ts
+++ b/client/src/game/controllers/aiController.ts
@@ -280,7 +280,16 @@ export function createAIController(config: AIControllerConfig): AIController {
     waitingFor: WaitingFor,
     state: GameState,
   ): Promise<GameAction | null> {
-    if (state.has_pending_cast) {
+    if (waitingFor.type === "ManaSourceSelection") {
+      const { adapter } = useGameStore.getState();
+      if (!adapter) return Promise.resolve(null);
+      return adapter.getLegalActions().then((result) => {
+        return result.actions.find((action) => action.type === "ActivateManaSource")
+          ?? result.actions.find((action) => action.type === "BackToManaPayment")
+          ?? null;
+      });
+    }
+    if (state.has_pending_cast && state.allows_cancel_cast) {
       return Promise.resolve({ type: "CancelCast" });
     }
     const { adapter } = useGameStore.getState();
diff --git a/client/src/game/waitingForRegistry.ts b/client/src/game/waitingForRegistry.ts
index b70f979ca5..e8dfb6b406 100644
--- a/client/src/game/waitingForRegistry.ts
+++ b/client/src/game/waitingForRegistry.ts
@@ -38,6 +38,7 @@ export const HANDLED_WAITING_FOR_TYPES: ReadonlySet<WaitingFor["type"]> =
     "MeldAttackTargetChoice",
     // Cast / activation chain — ManaPayment + PhyrexianPayment share ManaPaymentUI.
     ...MANA_PAYMENT_WAITING_FOR_TYPES,
+    "ManaSourceSelection",
     "ChooseXValue",
     "PayAmountChoice",
     "TargetSelection",
@@ -247,6 +248,7 @@ export function waitingForReason(
     case "RetargetChoice":
       return { key: "status.reason.choosingTargets" };
     case "ManaPayment":
+    case "ManaSourceSelection":
     case "PhyrexianPayment":
     case "PayCost":
     case "PayManaAbilityMana":
diff --git a/client/src/hooks/__tests__/useKeyboardShortcuts.test.tsx b/client/src/hooks/__tests__/useKeyboardShortcuts.test.tsx
index dce6c74109..9f3d26bcbc 100644
--- a/client/src/hooks/__tests__/useKeyboardShortcuts.test.tsx
+++ b/client/src/hooks/__tests__/useKeyboardShortcuts.test.tsx
@@ -132,6 +132,7 @@ describe("useKeyboardShortcuts", () => {
           source: { object_id: objectId, incarnation: 1 },
           ability_index: null,
           mana_type: "Green",
+          output: { type: "Concrete", data: "Green" },
           atomic_combination: null,
           restrictions: [],
           penalty: "None",
diff --git a/client/src/i18n/locales/de/game.json b/client/src/i18n/locales/de/game.json
index fb7f3e5988..fdba287aa7 100644
--- a/client/src/i18n/locales/de/game.json
+++ b/client/src/i18n/locales/de/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "Kann derzeit nicht aktiviert werden",
     "prohibited": "Das Aktivieren dieser Fähigkeit ist verboten"
   },
+  "manaSourceSelection": { "title": "Manaquelle wählen", "description": "Diese Manafähigkeit erfordert das Opfern einer bleibenden Karte.", "sacrifice": "Opfern", "back": "Zurück zur Manabezahlung", "unknownSource": "Manaquelle" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/de/settings.json b/client/src/i18n/locales/de/settings.json
index 70847ac630..d5699bd6af 100644
--- a/client/src/i18n/locales/de/settings.json
+++ b/client/src/i18n/locales/de/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Protokoll-Standard",
     "spellPayment": "Zauberspruch-Bezahlung",
     "manualManaPayment": "Manuelle Manabezahlung für Zaubersprüche",
+    "spellPaymentOptions": { "auto": "Automatisch", "autoExceptSacrificialMana": "Vor dem Opfern fragen", "manual": "Manuell" },
     "nativeEngine": "Native Engine für lokale Spiele und gehostete Mehrspielerpartien verwenden",
     "nativeEngineDescription": "Verwende die heruntergeladene Engine für lokale KI-Spiele und Spiele, die du über eine Lobby hostest. Gäste verbinden sich weiterhin über die Peer-to-Peer-Verbindung der Lobby. Fällt auf die integrierte Engine zurück, wenn sie nicht verfügbar ist.",
     "boardBackground": "Spielfeldhintergrund",
diff --git a/client/src/i18n/locales/en/game.json b/client/src/i18n/locales/en/game.json
index 2276c376b6..d22455282f 100644
--- a/client/src/i18n/locales/en/game.json
+++ b/client/src/i18n/locales/en/game.json
@@ -5,6 +5,13 @@
     "cantActivateDuring": "Can't be activated right now",
     "prohibited": "Activating this ability is prohibited"
   },
+  "manaSourceSelection": {
+    "title": "Choose a mana source",
+    "description": "This mana ability requires sacrificing a permanent.",
+    "sacrifice": "Sacrifice",
+    "back": "Back to mana payment",
+    "unknownSource": "Mana source"
+  },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/en/settings.json b/client/src/i18n/locales/en/settings.json
index c24b30e2a7..c8dd7ccf2e 100644
--- a/client/src/i18n/locales/en/settings.json
+++ b/client/src/i18n/locales/en/settings.json
@@ -29,6 +29,11 @@
     "logDefault": "Log Default",
     "spellPayment": "Spell Payment",
     "manualManaPayment": "Manual mana payment for spells",
+    "spellPaymentOptions": {
+      "auto": "Automatic",
+      "autoExceptSacrificialMana": "Ask before sacrificing",
+      "manual": "Manual"
+    },
     "nativeEngine": "Use native engine for local games and hosted multiplayer",
     "nativeEngineDescription": "Use the downloaded engine for local AI games and games you host through a lobby. Guests still connect through the lobby's peer-to-peer connection. Falls back to the built-in engine when unavailable.",
     "boardBackground": "Board Background",
diff --git a/client/src/i18n/locales/es/game.json b/client/src/i18n/locales/es/game.json
index 3d15c692c8..26e0897409 100644
--- a/client/src/i18n/locales/es/game.json
+++ b/client/src/i18n/locales/es/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "No puede activarse ahora",
     "prohibited": "Activar esta habilidad está prohibido"
   },
+  "manaSourceSelection": { "title": "Elige una fuente de maná", "description": "Esta habilidad de maná requiere sacrificar un permanente.", "sacrifice": "Sacrificar", "back": "Volver al pago de maná", "unknownSource": "Fuente de maná" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/es/settings.json b/client/src/i18n/locales/es/settings.json
index 56d809adff..e23ea850ed 100644
--- a/client/src/i18n/locales/es/settings.json
+++ b/client/src/i18n/locales/es/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Registro predeterminado",
     "spellPayment": "Pago de hechizos",
     "manualManaPayment": "Pago manual de maná para hechizos",
+    "spellPaymentOptions": { "auto": "Automático", "autoExceptSacrificialMana": "Preguntar antes de sacrificar", "manual": "Manual" },
     "nativeEngine": "Usar el motor nativo para partidas locales y multijugador alojado",
     "nativeEngineDescription": "Usa el motor descargado para partidas locales contra IA y partidas que alojes mediante una sala. Los invitados siguen conectándose mediante la conexión punto a punto de la sala. Usa el motor integrado cuando no está disponible.",
     "boardBackground": "Fondo del tablero",
diff --git a/client/src/i18n/locales/fr/game.json b/client/src/i18n/locales/fr/game.json
index 4435e8d67d..af9fcad115 100644
--- a/client/src/i18n/locales/fr/game.json
+++ b/client/src/i18n/locales/fr/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "Ne peut pas être activée pour l'instant",
     "prohibited": "L'activation de cette capacité est interdite"
   },
+  "manaSourceSelection": { "title": "Choisir une source de mana", "description": "Cette capacité de mana demande de sacrifier un permanent.", "sacrifice": "Sacrifier", "back": "Retour au paiement de mana", "unknownSource": "Source de mana" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/fr/settings.json b/client/src/i18n/locales/fr/settings.json
index f3c25aaf37..35f06d13eb 100644
--- a/client/src/i18n/locales/fr/settings.json
+++ b/client/src/i18n/locales/fr/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Journal par défaut",
     "spellPayment": "Paiement des sorts",
     "manualManaPayment": "Paiement manuel du mana pour les sorts",
+    "spellPaymentOptions": { "auto": "Automatique", "autoExceptSacrificialMana": "Demander avant de sacrifier", "manual": "Manuel" },
     "nativeEngine": "Utiliser le moteur natif pour les parties locales et le multijoueur hébergé",
     "nativeEngineDescription": "Utilisez le moteur téléchargé pour les parties locales contre l’IA et les parties que vous hébergez via un salon. Les invités se connectent toujours via la connexion pair à pair du salon. Utilise le moteur intégré lorsqu’il n’est pas disponible.",
     "boardBackground": "Arrière-plan du plateau",
diff --git a/client/src/i18n/locales/it/game.json b/client/src/i18n/locales/it/game.json
index 30a3c768c1..24aff1b0f9 100644
--- a/client/src/i18n/locales/it/game.json
+++ b/client/src/i18n/locales/it/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "Non può essere attivata ora",
     "prohibited": "L'attivazione di questa abilità è proibita"
   },
+  "manaSourceSelection": { "title": "Scegli una fonte di mana", "description": "Questa abilità di mana richiede di sacrificare un permanente.", "sacrifice": "Sacrifica", "back": "Torna al pagamento del mana", "unknownSource": "Fonte di mana" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/it/settings.json b/client/src/i18n/locales/it/settings.json
index 0f969c6722..ab047477e3 100644
--- a/client/src/i18n/locales/it/settings.json
+++ b/client/src/i18n/locales/it/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Registro predefinito",
     "spellPayment": "Pagamento magie",
     "manualManaPayment": "Pagamento manuale del mana per le magie",
+    "spellPaymentOptions": { "auto": "Automatico", "autoExceptSacrificialMana": "Chiedi prima di sacrificare", "manual": "Manuale" },
     "nativeEngine": "Usa il motore nativo per partite locali e multiplayer ospitato",
     "nativeEngineDescription": "Usa il motore scaricato per le partite locali contro l'IA e le partite che ospiti tramite una lobby. Gli ospiti continuano a connettersi tramite la connessione peer-to-peer della lobby. Usa il motore integrato quando non è disponibile.",
     "boardBackground": "Sfondo del campo",
diff --git a/client/src/i18n/locales/pl/game.json b/client/src/i18n/locales/pl/game.json
index c7acb281b3..1b28510c77 100644
--- a/client/src/i18n/locales/pl/game.json
+++ b/client/src/i18n/locales/pl/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "Nie można teraz aktywować",
     "prohibited": "Aktywacja tej zdolności jest zabroniona"
   },
+  "manaSourceSelection": { "title": "Wybierz źródło many", "description": "Ta zdolność many wymaga poświęcenia permanenta.", "sacrifice": "Poświęć", "back": "Wróć do płatności many", "unknownSource": "Źródło many" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/pl/settings.json b/client/src/i18n/locales/pl/settings.json
index 969d3dd454..1f3db39bf0 100644
--- a/client/src/i18n/locales/pl/settings.json
+++ b/client/src/i18n/locales/pl/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Domyślny dziennik",
     "spellPayment": "Płatność za czary",
     "manualManaPayment": "Ręczna płatność many za czary",
+    "spellPaymentOptions": { "auto": "Automatycznie", "autoExceptSacrificialMana": "Pytaj przed poświęceniem", "manual": "Ręcznie" },
     "nativeEngine": "Używaj natywnego silnika w lokalnych grach i hostowanym trybie wieloosobowym",
     "nativeEngineDescription": "Używaj pobranego silnika do lokalnych gier z AI i gier hostowanych przez lobby. Goście nadal łączą się przez połączenie peer-to-peer lobby. Gdy silnik jest niedostępny, używany jest wbudowany silnik.",
     "boardBackground": "Tło pola bitwy",
diff --git a/client/src/i18n/locales/pt/game.json b/client/src/i18n/locales/pt/game.json
index be12235a48..71fab73662 100644
--- a/client/src/i18n/locales/pt/game.json
+++ b/client/src/i18n/locales/pt/game.json
@@ -5,6 +5,7 @@
     "cantActivateDuring": "Não pode ser ativada agora",
     "prohibited": "Ativar esta habilidade é proibido"
   },
+  "manaSourceSelection": { "title": "Escolha uma fonte de mana", "description": "Esta habilidade de mana exige sacrificar uma permanente.", "sacrifice": "Sacrificar", "back": "Voltar ao pagamento de mana", "unknownSource": "Fonte de mana" },
   "comboShortcut": {
     "declareTitle": "Loop Shortcut",
     "declareSubtitle": "You control a loop with a determined outcome. Take the shortcut to resolve it.",
diff --git a/client/src/i18n/locales/pt/settings.json b/client/src/i18n/locales/pt/settings.json
index 508924e125..a7d3cac0ca 100644
--- a/client/src/i18n/locales/pt/settings.json
+++ b/client/src/i18n/locales/pt/settings.json
@@ -29,6 +29,7 @@
     "logDefault": "Registro Padrão",
     "spellPayment": "Pagamento de Mágicas",
     "manualManaPayment": "Pagamento manual de mana para mágicas",
+    "spellPaymentOptions": { "auto": "Automático", "autoExceptSacrificialMana": "Perguntar antes de sacrificar", "manual": "Manual" },
     "nativeEngine": "Usar o motor nativo para partidas locais e multijogador hospedado",
     "nativeEngineDescription": "Use o motor baixado para partidas locais contra IA e partidas hospedadas por você em um lobby. Os convidados continuam a se conectar pela conexão ponto a ponto do lobby. Usa o motor integrado quando não está disponível.",
     "boardBackground": "Plano de Fundo do Tabuleiro",
diff --git a/client/src/network/__tests__/protocol.test.ts b/client/src/network/__tests__/protocol.test.ts
index 8ba5036ed3..af7a4ad0e7 100644
--- a/client/src/network/__tests__/protocol.test.ts
+++ b/client/src/network/__tests__/protocol.test.ts
@@ -37,7 +37,7 @@ const viewerInteractionWithProducedMana = {
 
 describe("encodeWireMessage / decodeWireMessage", () => {
   it("pins the P2P wire protocol to v16", () => {
-    expect(WIRE_PROTOCOL_VERSION).toBe(16);
+    expect(WIRE_PROTOCOL_VERSION).toBe(17);
   });
 
   it("defaults shortcut actions for a legacy payload created before the additive field", () => {
diff --git a/client/src/network/protocol.ts b/client/src/network/protocol.ts
index 1ed4258c2e..4288b9f8c2 100644
--- a/client/src/network/protocol.ts
+++ b/client/src/network/protocol.ts
@@ -80,6 +80,7 @@ export function legalActionsFromWire(wire: LegalActionsWire): LegalActionsResult
  *   4 — Archenemy derived view and scheme deck payloads
  *   5 — CardPredicateGuessMade game event shape
  *  13 — Actor-scoped priority-passing settings and filtered per-player state.
+ *  17 — Sacrificial-mana source selection action and waiting-state snapshots.
  *  12 — Connive exact subject snapshots and resident paused post-replacement
  *       drains changed P2P GameState snapshots.
  *  11 — Serialized GameState trigger provenance and paused logical zone-change owners.
@@ -91,7 +92,7 @@ export function legalActionsFromWire(wire: LegalActionsWire): LegalActionsResult
  *       sub-phase on WaitingFor::MulliganDecision; the MulliganBottomCards
  *       variant was removed
  */
-export const WIRE_PROTOCOL_VERSION = 16 as const;
+export const WIRE_PROTOCOL_VERSION = 17 as const;
 
 export type P2PMessage =
   | { type: "guest_deck"; deckData: unknown; displayName?: string; reservationToken?: string }
diff --git a/client/src/pages/GamePage.tsx b/client/src/pages/GamePage.tsx
index 4564b8d73a..37a9084642 100644
--- a/client/src/pages/GamePage.tsx
+++ b/client/src/pages/GamePage.tsx
@@ -71,7 +71,7 @@ import { HelpSheet } from "../components/help/HelpSheet.tsx";
 import { GameLogPanel } from "../components/log/GameLogPanel.tsx";
 import { ChooseXValueUI } from "../components/mana/ChooseXValueUI.tsx";
 import { AssistPaymentUI } from "../components/mana/AssistPaymentUI.tsx";
-import { ManaPaymentUI } from "../components/mana/ManaPaymentUI.tsx";
+import { ManaPaymentUI, ManaSourceSelectionUI } from "../components/mana/ManaPaymentUI.tsx";
 import { PayAmountChoiceUI } from "../components/mana/PayAmountChoiceUI.tsx";
 import { RichLabel } from "../components/mana/RichLabel.tsx";
 import { CardDataMissingModal } from "../components/modal/CardDataMissingModal.tsx";
@@ -1770,6 +1770,8 @@ function GamePageContent({
         {waitingFor != null &&
           MANA_PAYMENT_WAITING_FOR_TYPES.has(waitingFor.type) &&
           canActForWaitingState && <ManaPaymentUI />}
+        {waitingFor?.type === "ManaSourceSelection" &&
+          canActForWaitingState && <ManaSourceSelectionUI />}
         {waitingFor?.type === "ChooseXValue" &&
           canActForWaitingState && <ChooseXValueUI />}
         {waitingFor?.type === "PayAmountChoice" &&
diff --git a/client/src/stores/preferencesStore.ts b/client/src/stores/preferencesStore.ts
index 3e81640d5f..31beb1c239 100644
--- a/client/src/stores/preferencesStore.ts
+++ b/client/src/stores/preferencesStore.ts
@@ -89,7 +89,7 @@ export type CommandZoneDisplay = "compact" | "inline" | "auto";
  *  tri-state "auto" precedent. Lands and support each carry their own value. */
 export type ZoneCollapseMode = "auto" | "on" | "off";
 export type TapRotation = "mtga" | "classic";
-export type SpellPaymentMode = "auto" | "manual";
+export type SpellPaymentMode = "auto" | "autoExceptSacrificialMana" | "manual";
 /** Which screen edge the resolving-stack panel docks to (and collapses toward).
  *  User-chosen so a player can keep the stack off whichever side of the
  *  battlefield they care about — e.g. dock left to free the right action rail. */
@@ -785,7 +785,7 @@ export const usePreferencesStore = create<PreferencesState & PreferencesActions>
     }),
     {
       name: "phase-preferences",
-      version: 28,
+      version: 29,
       // v0 → v1: flat aiDifficulty + aiDeckName become aiSeats[0].
       // v1 → v2: discrete animationSpeed/combatPacing enums become numeric
       //          animationSpeedMultiplier/combatPacingMultiplier.
@@ -845,6 +845,9 @@ export const usePreferencesStore = create<PreferencesState & PreferencesActions>
       //             preserves the intended enabled-by-default behavior.
       // v27 → v28: Add showCardPreviewFooter; legacy stores default to true
       //          via the shallow merge, preserving the prior presentation.
+      // v28 → v29: Add the sacrificial-mana-aware automatic mode. Existing
+      //          values remain valid; malformed persisted values normalize to
+      //          the legacy automatic behavior below.
       migrate: (persisted: unknown, version: number) => {
         if (!persisted || typeof persisted !== "object") return persisted;
         let migrated = persisted as Record<string, unknown>;
@@ -938,6 +941,17 @@ export const usePreferencesStore = create<PreferencesState & PreferencesActions>
           migrated = { ...migrated, spellPaymentMode: "auto" };
         }
 
+        if (version < 29) {
+          const mode = (migrated as { spellPaymentMode?: unknown }).spellPaymentMode;
+          migrated = {
+            ...migrated,
+            spellPaymentMode:
+              mode === "auto" || mode === "autoExceptSacrificialMana" || mode === "manual"
+                ? mode
+                : "auto",
+          };
+        }
+
         if (version < 9) {
           const lng = (migrated as { language?: unknown }).language;
           migrated = {
diff --git a/client/src/viewmodel/__tests__/cardActionChoice.test.ts b/client/src/viewmodel/__tests__/cardActionChoice.test.ts
index 869935a1a9..484728f715 100644
--- a/client/src/viewmodel/__tests__/cardActionChoice.test.ts
+++ b/client/src/viewmodel/__tests__/cardActionChoice.test.ts
@@ -66,6 +66,7 @@ function tapLandAction(objectId: number): Extract<GameAction, { type: "TapLandFo
         source: { object_id: objectId, incarnation: 1 },
         ability_index: null,
         mana_type: "Green",
+        output: { type: "Concrete", data: "Green" },
         atomic_combination: null,
         restrictions: [],
         penalty: "None",
diff --git a/crates/engine/src/ai_support/candidates.rs b/crates/engine/src/ai_support/candidates.rs
index a7b7e7a653..08bcde4e37 100644
--- a/crates/engine/src/ai_support/candidates.rs
+++ b/crates/engine/src/ai_support/candidates.rs
@@ -867,6 +867,27 @@ pub fn candidate_actions_broad_with_probe(
             player,
             convoke_mode,
         } => mana_payment_actions(state, *player, *convoke_mode),
+        WaitingFor::ManaSourceSelection {
+            player, options, ..
+        } => {
+            let mut actions = options
+                .iter()
+                .cloned()
+                .map(|selection| {
+                    candidate(
+                        GameAction::ActivateManaSource { selection },
+                        TacticalClass::Mana,
+                        Some(*player),
+                    )
+                })
+                .collect::<Vec<_>>();
+            actions.push(candidate(
+                GameAction::BackToManaPayment,
+                TacticalClass::Pass,
+                Some(*player),
+            ));
+            actions
+        }
         WaitingFor::MoveCountersDistribution {
             player,
             available,
@@ -3362,7 +3383,10 @@ fn semantic_candidate_actions_with_probe(
     let has_pending_cast = state.waiting_for.has_pending_cast()
         || (matches!(state.waiting_for, WaitingFor::DistributeAmong { .. })
             && state.pending_cast.is_some());
-    if has_pending_cast {
+    let allows_cancel_cast = state.waiting_for.allows_cancel_cast()
+        || (matches!(state.waiting_for, WaitingFor::DistributeAmong { .. })
+            && state.pending_cast.is_some());
+    if has_pending_cast && allows_cancel_cast {
         if let Some(player) = state.waiting_for.acting_player() {
             actions.push(candidate(
                 GameAction::CancelCast,
diff --git a/crates/engine/src/ai_support/filter.rs b/crates/engine/src/ai_support/filter.rs
index e833014569..f3b72621c6 100644
--- a/crates/engine/src/ai_support/filter.rs
+++ b/crates/engine/src/ai_support/filter.rs
@@ -1219,7 +1219,7 @@ fn legality_equivalence_key(
             key.is_blocked = crate::game::restrictions::is_source_blocked(state, *source_id);
             Some(key)
         }
-        GameAction::TapLandForMana { selection } => {
+        GameAction::TapLandForMana { selection } | GameAction::ActivateManaSource { selection } => {
             if poison.has_activation {
                 return None;
             }
diff --git a/crates/engine/src/ai_support/mod.rs b/crates/engine/src/ai_support/mod.rs
index f27f8d2e27..1c9d905387 100644
--- a/crates/engine/src/ai_support/mod.rs
+++ b/crates/engine/src/ai_support/mod.rs
@@ -188,6 +188,16 @@ fn cheap_reject_candidate(state: &GameState, action: &GameAction) -> bool {
                     },
             },
         )
+        | (
+            WaitingFor::Priority { .. },
+            GameAction::ActivateManaSource {
+                selection:
+                    crate::types::mana::ManaSourceSelection {
+                        source: crate::types::identifiers::ObjectIncarnationRef { object_id, .. },
+                        ..
+                    },
+            },
+        )
         | (WaitingFor::Priority { .. }, GameAction::UntapLandForMana { object_id })
         | (
             WaitingFor::Priority { .. },
@@ -1010,6 +1020,18 @@ fn grouped_mana_requires_priority(state: &GameState, player: PlayerId) -> bool {
                 &aura_sources,
                 &mana_activation_gates,
             ),
+            GameAction::ActivateManaSource { selection } => {
+                selection.ability_index.is_some_and(|ability_index| {
+                    activate_mana_action_would_queue_non_mana_trigger(
+                        state,
+                        player,
+                        selection.source.object_id,
+                        ability_index,
+                        &aura_sources,
+                        &mana_activation_gates,
+                    )
+                })
+            }
             _ => false,
         })
 }
@@ -1084,6 +1106,8 @@ fn classify_flat_priority_action(action: &GameAction) -> FlatPriorityActionClass
         | GameAction::MulliganDecision { .. }
         | GameAction::ReorderHand { .. }
         | GameAction::TapLandForMana { .. }
+        | GameAction::ActivateManaSource { .. }
+        | GameAction::BackToManaPayment
         | GameAction::UntapLandForMana { .. }
         | GameAction::SpendPoolMana { .. }
         | GameAction::UnspendPoolMana { .. }
@@ -1436,6 +1460,21 @@ fn beneficial_mana_tap_trigger_hold(
                 }
                 *source_id
             }
+            GameAction::ActivateManaSource { selection } => {
+                let Some(ability_index) = selection.ability_index else {
+                    return false;
+                };
+                let object_id = selection.source.object_id;
+                let has_tap = state
+                    .objects
+                    .get(&object_id)
+                    .and_then(|obj| obj.abilities.get(ability_index))
+                    .is_some_and(|ability| mana_sources::has_tap_component(&ability.cost));
+                if !has_tap {
+                    return false;
+                }
+                object_id
+            }
             _ => return false,
         };
 
diff --git a/crates/engine/src/ai_support/payment_continuation.rs b/crates/engine/src/ai_support/payment_continuation.rs
index c102286df8..60cb96d141 100644
--- a/crates/engine/src/ai_support/payment_continuation.rs
+++ b/crates/engine/src/ai_support/payment_continuation.rs
@@ -92,7 +92,9 @@ pub fn classify_payment_continuation(state: &GameState) -> PaymentContinuationSt
     match &state.waiting_for {
         // CR 601.2g–h: during the ordinary mana-payment window, the visible
         // payer and live pending cast jointly identify the payment root.
-        WaitingFor::ManaPayment { player, .. } => classify_global_root(state, *player),
+        WaitingFor::ManaPayment { player, .. } | WaitingFor::ManaSourceSelection { player, .. } => {
+            classify_global_root(state, *player)
+        }
         // CR 601.2f–h: submitting Phyrexian choices remains part of the same
         // cost payment. The prompt's object must agree with the announced root.
         WaitingFor::PhyrexianPayment {
@@ -442,6 +444,15 @@ fn classify_deferred_life_root(
                     PaymentContinuationUnsupported::PayerMismatch,
                 )
             }
+            ManaAbilityResume::ManaSourceSelection {
+                player: selection_player,
+                ..
+            } if selection_player == player => classify_global_root(state, *player),
+            ManaAbilityResume::ManaSourceSelection { .. } => {
+                PaymentContinuationState::UnsupportedAffiliated(
+                    PaymentContinuationUnsupported::PayerMismatch,
+                )
+            }
             ManaAbilityResume::PhyrexianCastPayment { .. }
             | ManaAbilityResume::FinalizePendingManaPayment { .. } => {
                 PaymentContinuationState::UnsupportedAffiliated(
@@ -532,6 +543,9 @@ fn record_root_from_resume(
         ManaAbilityResume::ManaPayment {
             outer_player: None, ..
         } => return Err(PaymentContinuationUnsupported::MissingOuterPayer),
+        ManaAbilityResume::ManaSourceSelection { player, .. } => {
+            Some(root_from_global(state, *player)?)
+        }
         ManaAbilityResume::PhyrexianCastPayment { caster, .. } => {
             Some(root_from_global(state, *caster)?)
         }
diff --git a/crates/engine/src/game/casting.rs b/crates/engine/src/game/casting.rs
index a932575ca3..7b567be050 100644
--- a/crates/engine/src/game/casting.rs
+++ b/crates/engine/src/game/casting.rs
@@ -15060,6 +15060,7 @@ fn auto_tap_and_pay_cost_excluding(
         Some(source_id),
         ctx,
         excluded_sources,
+        None,
         resume,
         parent,
     );
diff --git a/crates/engine/src/game/casting_costs.rs b/crates/engine/src/game/casting_costs.rs
index fb10c8f5a8..3a7eaf1e3e 100644
--- a/crates/engine/src/game/casting_costs.rs
+++ b/crates/engine/src/game/casting_costs.rs
@@ -8654,6 +8654,26 @@ pub(super) fn pay_and_push_adventure(
     }
 
     state.pending_cast = Some(Box::new(pending));
+    if payment_mode == CastPaymentMode::AutoExceptSacrificialMana {
+        auto_tap_non_sacrificial_mana_sources(state, player, cost, events, object_id);
+        if pending_cost_is_payable_from_pool(state, player) {
+            return finalize_automatic_mana_payment(state, player, events);
+        }
+        let options = super::mana_sources::activatable_mana_source_selections(state, player)
+            .into_iter()
+            .filter(|selection| {
+                selection.penalty == super::mana_sources::ManaSourcePenalty::Sacrifices
+            })
+            .collect::<Vec<_>>();
+        if options.is_empty() {
+            return enter_payment_step(state, player, None, events);
+        }
+        return Ok(WaitingFor::ManaSourceSelection {
+            player,
+            options,
+            convoke_mode: None,
+        });
+    }
     finalize_automatic_mana_payment(state, player, events)
 }
 
@@ -10375,6 +10395,7 @@ pub(super) fn auto_tap_mana_sources_excluding(
         None,
         None,
         None,
+        None,
     );
 }
 
@@ -10416,6 +10437,7 @@ pub(super) fn auto_tap_mana_sources_with_context_and_resume(
         deprioritize_source,
         payment_context,
         &HashSet::new(),
+        None,
         resume,
         None,
     );
@@ -10432,6 +10454,7 @@ pub(super) fn auto_tap_mana_sources_with_context_excluding_and_resume(
     deprioritize_source: Option<ObjectId>,
     payment_context: Option<&PaymentContext<'_>>,
     excluded_sources: &HashSet<ObjectId>,
+    excluded_penalty: Option<mana_sources::ManaSourcePenalty>,
     resume: Option<&ManaAbilityResume>,
     parent: Option<&ManaAbilityCostParent>,
 ) {
@@ -10442,6 +10465,7 @@ pub(super) fn auto_tap_mana_sources_with_context_excluding_and_resume(
         events,
         deprioritize_source,
         excluded_sources,
+        excluded_penalty,
         payment_context,
         None,
         None,
@@ -10466,6 +10490,7 @@ pub(super) fn auto_tap_mana_sources_with_context_excluding(
         events,
         deprioritize_source,
         excluded_sources,
+        None,
         payment_context,
         None,
         None,
@@ -10474,6 +10499,63 @@ pub(super) fn auto_tap_mana_sources_with_context_excluding(
     );
 }
 
+/// CR 601.2g-h + CR 605.3b: Apply the existing automatic planner while
+/// excluding sacrificial activation rows. This is the safe first leg of
+/// `AutoExceptSacrificialMana`; the caller retains the pending cast and offers
+/// the excluded capabilities explicitly if this leg cannot finish payment.
+pub(super) fn auto_tap_non_sacrificial_mana_sources(
+    state: &mut GameState,
+    player: PlayerId,
+    cost: &crate::types::mana::ManaCost,
+    events: &mut Vec<GameEvent>,
+    source_id: ObjectId,
+) {
+    let spell_meta = super::casting::build_spell_meta(state, player, source_id);
+    let spell_ctx = spell_meta.as_ref().map(PaymentContext::Spell);
+    auto_tap_mana_sources_inner(
+        state,
+        player,
+        cost,
+        events,
+        Some(source_id),
+        &HashSet::new(),
+        Some(mana_sources::ManaSourcePenalty::Sacrifices),
+        spell_ctx.as_ref(),
+        None,
+        None,
+        None,
+        None,
+    );
+}
+
+pub(super) fn pending_cost_is_payable_from_pool(state: &GameState, player: PlayerId) -> bool {
+    let Some(pending) = state.pending_cast.as_deref() else {
+        return false;
+    };
+    let spell_meta = super::casting::build_spell_meta(state, player, pending.object_id);
+    let spell_ctx = spell_meta.as_ref().map(PaymentContext::Spell);
+    let any_color = super::casting::player_can_spend_as_any_color_for_payment(
+        state,
+        player,
+        Some(pending.object_id),
+        spell_ctx.as_ref(),
+    );
+    let permissions =
+        super::static_abilities::build_cost_permission_context(state, player, any_color);
+    state
+        .players
+        .iter()
+        .find(|candidate| candidate.id == player)
+        .is_some_and(|candidate| {
+            mana_payment::can_pay_for_spell(
+                &candidate.mana_pool,
+                &pending.cost,
+                spell_ctx.as_ref(),
+                permissions,
+            )
+        })
+}
+
 #[derive(Debug, Clone)]
 pub(super) struct AutoTapSourceCache {
     player: PlayerId,
@@ -10503,7 +10585,7 @@ pub(super) fn build_auto_tap_source_cache(
     crate::game::perf_counters::record_auto_tap_source_cache_build();
     AutoTapSourceCache {
         player,
-        sources: collect_sorted_auto_tap_source_options(state, player, None, &HashSet::new()),
+        sources: collect_sorted_auto_tap_source_options(state, player, None, &HashSet::new(), None),
     }
 }
 
@@ -10525,6 +10607,7 @@ pub(super) fn auto_tap_mana_sources_with_context_excluding_cached(
         events,
         deprioritize_source,
         excluded_sources,
+        None,
         payment_context,
         None,
         source_cache,
@@ -10538,6 +10621,7 @@ fn collect_sorted_auto_tap_source_options(
     player: PlayerId,
     deprioritize_source: Option<ObjectId>,
     excluded_sources: &HashSet<ObjectId>,
+    excluded_penalty: Option<mana_sources::ManaSourcePenalty>,
 ) -> Vec<ManaSourceOption> {
     use crate::types::card_type::{CoreType, Supertype};
 
@@ -10593,6 +10677,7 @@ fn collect_sorted_auto_tap_source_options(
             }
         })
         .flatten()
+        .filter(|option| excluded_penalty.is_none_or(|penalty| option.penalty != penalty))
         .collect();
 
     // CR 605.3b: Auto-tap sort key. Tier layout (the enum factors the two
@@ -10675,11 +10760,13 @@ fn cached_auto_tap_sources<'a>(
     player: PlayerId,
     deprioritize_source: Option<ObjectId>,
     excluded_sources: &HashSet<ObjectId>,
+    excluded_penalty: Option<mana_sources::ManaSourcePenalty>,
     sub_cost_demand: Option<&crate::game::mana_payment::ColorDemand>,
 ) -> Option<&'a [ManaSourceOption]> {
     let cache = source_cache?;
     if cache.is_for_player(player)
         && excluded_sources.is_empty()
+        && excluded_penalty.is_none()
         && sub_cost_demand.is_none()
         && deprioritize_source.is_none_or(|source_id| !cache.contains_source(source_id))
     {
@@ -10699,6 +10786,7 @@ fn auto_tap_mana_sources_inner(
     events: &mut Vec<GameEvent>,
     deprioritize_source: Option<ObjectId>,
     excluded_sources: &HashSet<ObjectId>,
+    excluded_penalty: Option<mana_sources::ManaSourcePenalty>,
     payment_context: Option<&PaymentContext<'_>>,
     sub_cost_demand: Option<&crate::game::mana_payment::ColorDemand>,
     source_cache: Option<&AutoTapSourceCache>,
@@ -10756,6 +10844,7 @@ fn auto_tap_mana_sources_inner(
         player,
         deprioritize_source,
         excluded_sources,
+        excluded_penalty,
         sub_cost_demand,
     ) {
         cached
@@ -10765,6 +10854,7 @@ fn auto_tap_mana_sources_inner(
             player,
             deprioritize_source,
             excluded_sources,
+            excluded_penalty,
         );
         &available_buf
     };
@@ -11111,6 +11201,7 @@ fn auto_tap_mana_sources_inner(
                         events,
                         Some(option.object_id),
                         excluded,
+                        excluded_penalty,
                         Some(&activation_ctx),
                         demand.as_ref(),
                         None,
@@ -12871,6 +12962,7 @@ pub(super) fn maybe_pause_for_phyrexian_choice(
             Some(source_id),
             payment_context,
             excluded_sources,
+            None,
             resume,
             None,
         );
diff --git a/crates/engine/src/game/costs.rs b/crates/engine/src/game/costs.rs
index 5174665a0a..48dfdb0649 100644
--- a/crates/engine/src/game/costs.rs
+++ b/crates/engine/src/game/costs.rs
@@ -423,6 +423,11 @@ fn effect_pay_cost_mana_resume(
     if let WaitingFor::ManaPayment {
         player,
         convoke_mode,
+    }
+    | WaitingFor::ManaSourceSelection {
+        player,
+        convoke_mode,
+        ..
     } = &state.waiting_for
     {
         return Some(ManaAbilityResume::ManaPayment {
diff --git a/crates/engine/src/game/derived.rs b/crates/engine/src/game/derived.rs
index 314a726d0d..f353b01279 100644
--- a/crates/engine/src/game/derived.rs
+++ b/crates/engine/src/game/derived.rs
@@ -289,6 +289,9 @@ pub fn derive_display_state(state: &mut GameState) {
     state.has_pending_cast = state.waiting_for.has_pending_cast()
         || (matches!(state.waiting_for, WaitingFor::DistributeAmong { .. })
             && state.pending_cast.is_some());
+    state.allows_cancel_cast = state.waiting_for.allows_cancel_cast()
+        || (matches!(state.waiting_for, WaitingFor::DistributeAmong { .. })
+            && state.pending_cast.is_some());
 
     // Invariant: the two storage sites for "am I mid-cast" must agree. If
     // `waiting_for` says we're mid-cast, `GameState::pending_cast` must be
diff --git a/crates/engine/src/game/effects/prepare.rs b/crates/engine/src/game/effects/prepare.rs
index 9998257446..de3bbc98a4 100644
--- a/crates/engine/src/game/effects/prepare.rs
+++ b/crates/engine/src/game/effects/prepare.rs
@@ -344,7 +344,9 @@ fn mark_prepare_copy_cancel_rollback(
 
     if matches!(
         waiting,
-        WaitingFor::ManaPayment { .. } | WaitingFor::PhyrexianPayment { .. }
+        WaitingFor::ManaPayment { .. }
+            | WaitingFor::ManaSourceSelection { .. }
+            | WaitingFor::PhyrexianPayment { .. }
     ) {
         if let Some(pending) = state.pending_cast.as_mut() {
             debug_assert_eq!(
diff --git a/crates/engine/src/game/engine.rs b/crates/engine/src/game/engine.rs
index 7ff86d769a..d92b89085d 100644
--- a/crates/engine/src/game/engine.rs
+++ b/crates/engine/src/game/engine.rs
@@ -4477,6 +4477,48 @@ fn apply_action(
             );
             waiting_for
         }
+        (WaitingFor::Priority { player }, GameAction::ActivateManaSource { selection }) => {
+            if state.priority_player
+                != turn_control::authorized_submitter_for_player(state, *player)
+            {
+                return Err(EngineError::NotYourPriority);
+            }
+            if state
+                .objects
+                .get(&selection.source.object_id)
+                .is_some_and(|object| {
+                    object
+                        .card_types
+                        .core_types
+                        .contains(&crate::types::card_type::CoreType::Land)
+                })
+            {
+                return Err(EngineError::ActionNotAllowed(
+                    "Land mana abilities use TapLandForMana".to_string(),
+                ));
+            }
+            let events_before = events.len();
+            let waiting_for = mana_sources::activate_mana_source_selection(
+                state,
+                *player,
+                &selection,
+                &mut events,
+                ManaAbilityResume::Priority,
+            )?;
+            triggers::resolve_tap_mana_triggers_inline(state, &mut events, events_before);
+            if let Some(ability_index) = selection.ability_index {
+                record_mana_loop_action_step(
+                    state,
+                    *player,
+                    selection.source.object_id,
+                    crate::types::game_state::LoopAction::Activate {
+                        source_id: selection.source.object_id,
+                        ability_index,
+                    },
+                );
+            }
+            waiting_for
+        }
         (WaitingFor::Priority { player }, GameAction::UntapLandForMana { object_id }) => {
             if state.priority_player
                 != turn_control::authorized_submitter_for_player(state, *player)
@@ -6055,6 +6097,49 @@ fn apply_action(
                 None => WaitingFor::Priority { player },
             }
         }
+        (
+            WaitingFor::ManaSourceSelection {
+                player,
+                options,
+                convoke_mode,
+            },
+            GameAction::BackToManaPayment,
+        ) => {
+            // The selection window never consumes mana or changes pins. Restore
+            // the exact payment state rather than re-running the planner.
+            let _ = options;
+            WaitingFor::ManaPayment {
+                player: *player,
+                convoke_mode: *convoke_mode,
+            }
+        }
+        (
+            WaitingFor::ManaSourceSelection {
+                player,
+                options,
+                convoke_mode,
+            },
+            GameAction::ActivateManaSource { selection },
+        ) => {
+            if !options.contains(&selection) {
+                return Err(EngineError::ActionNotAllowed(
+                    "Mana source was not offered for this payment".to_string(),
+                ));
+            }
+            let events_before = events.len();
+            let waiting_for = mana_sources::activate_mana_source_selection(
+                state,
+                *player,
+                &selection,
+                &mut events,
+                ManaAbilityResume::ManaPayment {
+                    outer_player: Some(*player),
+                    convoke_mode: *convoke_mode,
+                },
+            )?;
+            triggers::resolve_tap_mana_triggers_inline(state, &mut events, events_before);
+            waiting_for
+        }
         (WaitingFor::ChooseXValue { player, .. }, GameAction::CancelCast) => {
             // CR 601.2f + CR 601.2i: Caster may back out before committing to an
             // X value. Pop the stack entry placed at announcement and restore.
diff --git a/crates/engine/src/game/interaction.rs b/crates/engine/src/game/interaction.rs
index 68a1a2b932..b7826e2004 100644
--- a/crates/engine/src/game/interaction.rs
+++ b/crates/engine/src/game/interaction.rs
@@ -248,7 +248,9 @@ fn human_response_model(waiting_for: &WaitingFor, semantic_owner: PlayerId) -> H
         | WaitingFor::CommanderZoneChoice { .. }
         | WaitingFor::UntapChoice { .. } => HumanResponseModel::DirectChoices,
         WaitingFor::BetweenGamesSideboard { .. } => HumanResponseModel::SideboardPartition,
-        WaitingFor::ManaPayment { .. } => HumanResponseModel::DirectChoices,
+        WaitingFor::ManaPayment { .. } | WaitingFor::ManaSourceSelection { .. } => {
+            HumanResponseModel::DirectChoices
+        }
         WaitingFor::LoopShortcut { .. } => HumanResponseModel::LoopShortcut,
         WaitingFor::Priority { .. }
         | WaitingFor::MeldPairChoice { .. }
@@ -334,6 +336,7 @@ fn classify_waiting_for(waiting_for: &WaitingFor) -> WaitingClassification {
             Some(InteractionSlotKind::OpeningBottom),
         ),
         WaitingFor::ManaPayment { .. }
+        | WaitingFor::ManaSourceSelection { .. }
         | WaitingFor::AssistPayment { .. }
         | WaitingFor::DefilerPayment { .. }
         | WaitingFor::UnlessPayment { .. }
@@ -2008,6 +2011,20 @@ fn direct_choice_projection(
             }
             mana_payment_direct_actions(state, *player, *convoke_mode)?
         }
+        WaitingFor::ManaSourceSelection {
+            player, options, ..
+        } => {
+            if *player != semantic_owner {
+                return Err(InteractionReasonCode::InvalidAuthorityState);
+            }
+            let mut actions = options
+                .iter()
+                .cloned()
+                .map(|selection| GameAction::ActivateManaSource { selection })
+                .collect::<Vec<_>>();
+            actions.push(GameAction::BackToManaPayment);
+            actions
+        }
         WaitingFor::PrecastCopyShortcutOffer {
             epoch, route_count, ..
         } => {
@@ -3351,6 +3368,7 @@ fn selection_projection(
         | WaitingFor::MeldPairChoice { .. }
         | WaitingFor::MeldAttackTargetChoice { .. }
         | WaitingFor::ManaPayment { .. }
+        | WaitingFor::ManaSourceSelection { .. }
         | WaitingFor::AssistChoosePlayer { .. }
         | WaitingFor::AssistPayment { .. }
         | WaitingFor::ChooseXValue { .. }
@@ -3873,6 +3891,7 @@ fn object_property_code(property: ObjectProperty) -> InteractionObjectProperty {
 fn cast_payment_mode_code(mode: CastPaymentMode) -> &'static str {
     match mode {
         CastPaymentMode::Auto => "auto",
+        CastPaymentMode::AutoExceptSacrificialMana => "autoExceptSacrificialMana",
         CastPaymentMode::Manual => "manual",
     }
 }
@@ -4146,6 +4165,7 @@ fn project_action_payload(
     match action {
         GameAction::PassPriority
         | GameAction::CancelCast
+        | GameAction::BackToManaPayment
         | GameAction::KeepAllCopyTargets
         | GameAction::RollPlanarDie
         | GameAction::CompanionToHand
@@ -4157,7 +4177,7 @@ fn project_action_payload(
         GameAction::ChooseEntryAttackTarget { target } => {
             push_attack_target_surface(surfaces, state, target, InteractionRoleCode::AttackTarget)
         }
-        GameAction::TapLandForMana { selection } => {
+        GameAction::TapLandForMana { selection } | GameAction::ActivateManaSource { selection } => {
             let Some(player) = state
                 .objects
                 .get(&selection.source.object_id)
@@ -4166,7 +4186,7 @@ fn project_action_payload(
                 return;
             };
             let Ok(option) =
-                mana_sources::live_land_mana_option_for_selection(state, player, selection)
+                mana_sources::live_mana_source_option_for_selection(state, player, selection)
             else {
                 return;
             };
@@ -4969,6 +4989,8 @@ fn action_code(action: &GameAction) -> InteractionActionCode {
         GameAction::MulliganDecision { .. } => InteractionActionCode::MulliganDecision,
         GameAction::ReorderHand { .. } => InteractionActionCode::ReorderHand,
         GameAction::TapLandForMana { .. } => InteractionActionCode::TapLandForMana,
+        GameAction::ActivateManaSource { .. } => InteractionActionCode::ActivateManaSource,
+        GameAction::BackToManaPayment => InteractionActionCode::BackToManaPayment,
         GameAction::UntapLandForMana { .. } => InteractionActionCode::UntapLandForMana,
         GameAction::SpendPoolMana { .. } => InteractionActionCode::SpendPoolMana,
         GameAction::UnspendPoolMana { .. } => InteractionActionCode::UnspendPoolMana,
@@ -5137,7 +5159,7 @@ fn actor_candidates(
         .filter_map(|candidate| {
             let mut manual = candidate.clone();
             let payment_mode = manual.action.payment_mode_mut()?;
-            if *payment_mode != CastPaymentMode::Auto {
+            if *payment_mode == CastPaymentMode::Manual {
                 return None;
             }
             *payment_mode = CastPaymentMode::Manual;
diff --git a/crates/engine/src/game/mana_abilities.rs b/crates/engine/src/game/mana_abilities.rs
index 5795d85d37..941815d24a 100644
--- a/crates/engine/src/game/mana_abilities.rs
+++ b/crates/engine/src/game/mana_abilities.rs
@@ -2752,6 +2752,18 @@ pub(crate) fn finish_mana_root_after_deferred_life_payment(
                 convoke_mode,
             },
         )),
+        ManaAbilityResume::ManaSourceSelection {
+            player,
+            options,
+            convoke_mode,
+        } => Ok(resume_waiting_for(
+            player,
+            ManaAbilityResume::ManaSourceSelection {
+                player,
+                options,
+                convoke_mode,
+            },
+        )),
         ManaAbilityResume::UnlessPayment {
             outer_player,
             cost,
@@ -4152,6 +4164,15 @@ pub(crate) fn resume_waiting_for(
             player: outer_player.unwrap_or(mana_source_controller),
             convoke_mode,
         },
+        ManaAbilityResume::ManaSourceSelection {
+            player,
+            options,
+            convoke_mode,
+        } => WaitingFor::ManaSourceSelection {
+            player,
+            options,
+            convoke_mode,
+        },
         ManaAbilityResume::UnlessPayment {
             outer_player,
             cost,
diff --git a/crates/engine/src/game/mana_sources.rs b/crates/engine/src/game/mana_sources.rs
index e9370ebee7..aeabe1a72a 100644
--- a/crates/engine/src/game/mana_sources.rs
+++ b/crates/engine/src/game/mana_sources.rs
@@ -26,8 +26,8 @@ use crate::types::events::{GameEvent, ManaTapState};
 use crate::types::game_state::{GameState, ManaAbilityResume, ProductionOverride, WaitingFor};
 use crate::types::identifiers::ObjectId;
 use crate::types::mana::{
-    ManaColor, ManaCostShard, ManaPip, ManaRestriction, ManaSourceSelection, ManaType,
-    PaymentContext, TapsForManaSelection,
+    ManaColor, ManaCostShard, ManaPip, ManaRestriction, ManaSourceOutput, ManaSourceSelection,
+    ManaType, PaymentContext, TapsForManaSelection,
 };
 use crate::types::player::PlayerId;
 use crate::types::zones::Zone;
@@ -203,6 +203,7 @@ impl ManaSourceOption {
             source: crate::types::identifiers::ObjectIncarnationRef::from_object(source),
             ability_index: self.ability_index,
             mana_type: self.mana_type,
+            output: ManaSourceOutput::Concrete(self.mana_type),
             atomic_combination: self.atomic_combination.clone(),
             restrictions: self.restrictions.clone(),
             penalty: self.penalty,
@@ -297,6 +298,10 @@ pub fn activatable_mana_actions_for_player(state: &GameState, player: PlayerId)
                     &mana_activation_gates,
                 )
             {
+                // Interactive costs (for example, "Sacrifice an artifact")
+                // deliberately remain the ordinary activation action during a
+                // normal ManaPayment window. Its established cost resolver is
+                // the authority for the subsequent PayCost choice.
                 actions.push(GameAction::ActivateAbility {
                     source_id: object_id,
                     ability_index,
@@ -307,6 +312,181 @@ pub fn activatable_mana_actions_for_player(state: &GameState, player: PlayerId)
     actions
 }
 
+/// CR 605.3a: Complete semantic capabilities for mana activation, across lands
+/// and nonlands. This is intentionally separate from `GameAction` generation:
+/// callers can freeze these engine-authored candidates in an interaction and
+/// later require an exact fresh match before activation.
+pub fn activatable_mana_source_selections(
+    state: &GameState,
+    player: PlayerId,
+) -> Vec<ManaSourceSelection> {
+    let aura_sources = taps_for_mana_trigger_sources(state);
+    let gates = mana_abilities::ManaActivationGates::compute(state);
+    let mut selections = Vec::new();
+
+    for &object_id in &state.battlefield {
+        let Some(object) = state.objects.get(&object_id) else {
+            continue;
+        };
+        if object.controller != player {
+            continue;
+        }
+
+        let options = current_mana_source_options(state, player, object_id, &aura_sources, &gates);
+        for option in options {
+            let Some(selection) = manual_selection_for_option(state, &option) else {
+                continue;
+            };
+            if !selections.contains(&selection) {
+                selections.push(selection);
+            }
+        }
+    }
+    selections.sort_by(|left, right| left.cmp_stable(right));
+    selections
+}
+
+/// CR 605.3a: Return the source rows a frozen, explicit mana selection may
+/// name. Auto-tap rows stay the base because they preserve land fallback and
+/// tap-trigger metadata; then append every other currently legal activated
+/// mana ability. Unlike the automatic planner, this includes interactive costs
+/// such as "Sacrifice an artifact", because the selection is explicit and the
+/// normal `PayCost` flow still resolves that cost after activation.
+fn current_mana_source_options(
+    state: &GameState,
+    player: PlayerId,
+    object_id: ObjectId,
+    aura_sources: &[ObjectId],
+    gates: &mana_abilities::ManaActivationGates,
+) -> Vec<ManaSourceOption> {
+    let Some(object) = state.objects.get(&object_id) else {
+        return Vec::new();
+    };
+    if object.zone != Zone::Battlefield || object.controller != player {
+        return Vec::new();
+    }
+
+    let mut options = if object.card_types.core_types.contains(&CoreType::Land) {
+        activatable_land_mana_options_indexed_gated(state, object_id, player, aura_sources, gates)
+    } else {
+        auto_tap_mana_options(state, object_id, player)
+    };
+
+    for (ability_index, ability) in object.abilities.iter().enumerate() {
+        if options
+            .iter()
+            .any(|option| option.ability_index == Some(ability_index))
+            || ability.kind != AbilityKind::Activated
+            || !mana_abilities::is_mana_ability(ability)
+            || !mana_abilities::can_activate_mana_ability_now_gated(
+                state,
+                player,
+                object_id,
+                ability_index,
+                ability,
+                gates,
+            )
+            || !activation_condition_satisfied(state, player, object_id, ability_index, ability)
+        {
+            continue;
+        }
+
+        let penalty = object_mana_ability_penalty(state, object_id, ability);
+        let source_could_produce_two_or_more_colors =
+            source_could_produce_two_or_more_colors(state, object_id, player);
+        for row in emit_source_rows(state, player, object_id, ability_index, ability, true) {
+            let option = ManaSourceOption {
+                object_id,
+                ability_index: Some(ability_index),
+                mana_type: row.mana_type,
+                source_could_produce_two_or_more_colors,
+                penalty,
+                atomic_combination: row.atomic_combination,
+                restrictions: row.restrictions,
+                taps_for_mana_overrides: Vec::new(),
+            };
+            if !options.contains(&option) {
+                options.push(option);
+            }
+        }
+    }
+
+    options
+}
+
+fn manual_selection_for_option(
+    state: &GameState,
+    option: &ManaSourceOption,
+) -> Option<ManaSourceSelection> {
+    let mut selection = option.semantic_selection(state)?;
+    let flexible_output = option.ability_index.is_some_and(|ability_index| {
+        state
+            .objects
+            .get(&option.object_id)
+            .and_then(|object| object.abilities.get(ability_index))
+            .is_some_and(|ability| {
+                matches!(
+                    &*ability.effect,
+                    Effect::Mana {
+                        produced: ManaProduction::AnyOneColor { .. }
+                            | ManaProduction::AnyCombination { .. }
+                            | ManaProduction::ChoiceAmongExiledColors { .. }
+                            | ManaProduction::AnyOneColorAmongPermanents { .. }
+                            | ManaProduction::OpponentLandColors { .. }
+                            | ManaProduction::AnyTypeProduceableBy { .. }
+                            | ManaProduction::AnyCombinationOfObjectColors { .. }
+                            | ManaProduction::AnyInCommandersColorIdentity { .. },
+                        ..
+                    }
+                )
+            })
+    });
+    if flexible_output {
+        // The planner emits one concrete row per color, but a manual activation
+        // must retain the source capability and let the normal mana-choice
+        // resolver ask for its color. The colorless marker is intentionally
+        // inert while `output` is deferred and canonicalizes all planner rows.
+        selection.mana_type = ManaType::Colorless;
+        selection.output = ManaSourceOutput::DeferredColorChoice;
+    }
+    Some(selection)
+}
+
+/// Resolve an exact generic semantic source selection from fresh candidates.
+/// A deferred flexible output legitimately corresponds to several concrete
+/// planner rows; they all name the same object/ability capability and therefore
+/// collapse to one canonical manual selection above.
+pub(crate) fn live_mana_source_option_for_selection(
+    state: &GameState,
+    player: PlayerId,
+    selection: &ManaSourceSelection,
+) -> Result<ManaSourceOption, EngineError> {
+    if !activatable_mana_source_selections(state, player).contains(selection) {
+        return Err(EngineError::ActionNotAllowed(
+            "Mana source selection is stale or no longer legal".to_string(),
+        ));
+    }
+
+    let aura_sources = taps_for_mana_trigger_sources(state);
+    let gates = mana_abilities::ManaActivationGates::compute(state);
+    let object_id = selection.source.object_id;
+    let options = current_mana_source_options(state, player, object_id, &aura_sources, &gates);
+    let mut matches = options
+        .into_iter()
+        .filter(|option| manual_selection_for_option(state, option).as_ref() == Some(selection));
+    let option = matches.next().ok_or_else(|| {
+        EngineError::ActionNotAllowed(
+            "Mana source selection is stale or no longer legal".to_string(),
+        )
+    })?;
+    if matches.any(|other| other.ability_index != option.ability_index) {
+        return Err(EngineError::InvalidAction(
+            "Mana source selection ambiguously matches multiple live capabilities".to_string(),
+        ));
+    }
+    Ok(option)
+}
+
 /// Re-enumerate the live land-mana rows and resolve one exact semantic
 /// selection to its current engine-owned option. Zero matches means the
 /// submitted choice is stale or illegal; multiple matches mean the selector
@@ -551,6 +731,27 @@ pub(crate) fn activate_mana_source_option(
     option: &ManaSourceOption,
     events: &mut Vec<GameEvent>,
     resume: ManaAbilityResume,
+) -> Result<WaitingFor, EngineError> {
+    activate_mana_source_option_with_output(
+        state,
+        player,
+        option,
+        ManaSourceOutput::Concrete(option.mana_type),
+        events,
+        resume,
+    )
+}
+
+/// Activate a live source using the preserved output provenance. Deferred
+/// flexible outputs deliberately pass no production override, so the existing
+/// ManaChoice flow remains the single authority for the eventual color choice.
+pub(crate) fn activate_mana_source_option_with_output(
+    state: &mut GameState,
+    player: PlayerId,
+    option: &ManaSourceOption,
+    output: ManaSourceOutput,
+    events: &mut Vec<GameEvent>,
+    resume: ManaAbilityResume,
 ) -> Result<WaitingFor, EngineError> {
     for (trigger_ref, production_override) in &option.taps_for_mana_overrides {
         state
@@ -569,8 +770,12 @@ pub(crate) fn activate_mana_source_option(
                     "Selected mana ability is no longer available".to_string(),
                 )
             })?;
-        let production_override =
-            super::casting_costs::production_override_for_option(&ability, option);
+        let production_override = match output {
+            ManaSourceOutput::Concrete(_) => {
+                super::casting_costs::production_override_for_option(&ability, option)
+            }
+            ManaSourceOutput::DeferredColorChoice => None,
+        };
         mana_abilities::activate_mana_ability(
             state,
             option.object_id,
@@ -630,6 +835,28 @@ pub(crate) fn activate_mana_source_option(
     Ok(waiting_for)
 }
 
+/// CR 605.3a-b: Revalidate and activate a generic mana capability. The caller
+/// supplies its resume because this entry point is shared by priority and a
+/// spell's mana-payment interaction; it never translates back into
+/// `ActivateAbility`, preserving the frozen selection identity.
+pub(crate) fn activate_mana_source_selection(
+    state: &mut GameState,
+    player: PlayerId,
+    selection: &ManaSourceSelection,
+    events: &mut Vec<GameEvent>,
+    resume: ManaAbilityResume,
+) -> Result<WaitingFor, EngineError> {
+    let option = live_mana_source_option_for_selection(state, player, selection)?;
+    activate_mana_source_option_with_output(
+        state,
+        player,
+        &option,
+        selection.output,
+        events,
+        resume,
+    )
+}
+
 /// CR 107.6 + CR 302.6: True when the cost includes the untap symbol ({Q}).
 /// Like {T}, a {Q} cost on a creature is gated by summoning sickness (CR 302.6
 /// names both symbols) and requires the source to currently be tapped. Matches a
diff --git a/crates/engine/src/game/replay.rs b/crates/engine/src/game/replay.rs
index 466c72d61a..107a8de281 100644
--- a/crates/engine/src/game/replay.rs
+++ b/crates/engine/src/game/replay.rs
@@ -212,7 +212,7 @@ mod tests {
     use crate::types::game_state::{ProductionOverride, WaitingFor};
     use crate::types::identifiers::{ObjectId, ObjectIncarnationRef};
     use crate::types::mana::{
-        ManaSourcePenalty, ManaSourceSelection, ManaType, TapsForManaSelection,
+        ManaSourceOutput, ManaSourcePenalty, ManaSourceSelection, ManaType, TapsForManaSelection,
     };
     use crate::types::match_config::MatchConfig;
 
@@ -267,6 +267,7 @@ mod tests {
                 source,
                 ability_index: None,
                 mana_type: ManaType::Green,
+                output: crate::types::mana::ManaSourceOutput::Concrete(ManaType::Green),
                 atomic_combination: None,
                 restrictions: Vec::new(),
                 penalty: ManaSourcePenalty::None,
@@ -291,6 +292,34 @@ mod tests {
         assert_eq!(restored.actions[0].action, action);
     }
 
+    #[test]
+    fn legacy_colored_tap_land_action_preserves_its_selected_output() {
+        let action: GameAction = serde_json::from_value(serde_json::json!({
+            "type": "TapLandForMana",
+            "data": {
+                "selection": {
+                    "source": { "object_id": 7, "incarnation": 3 },
+                    "ability_index": null,
+                    "mana_type": "Green",
+                    "atomic_combination": null,
+                    "restrictions": [],
+                    "penalty": "None",
+                    "taps_for_mana": []
+                }
+            }
+        }))
+        .expect("pre-output replay actions should deserialize");
+
+        let GameAction::TapLandForMana { selection } = action else {
+            panic!("legacy action must retain its TapLandForMana shape");
+        };
+        assert_eq!(
+            selection.output,
+            ManaSourceOutput::Concrete(ManaType::Green),
+            "a legacy colored row selected its mana_type, not colorless mana"
+        );
+    }
+
     #[test]
     fn replay_player_reconstructs_every_recorded_index() {
         let header = two_player_header(99);
diff --git a/crates/engine/src/game/scenario.rs b/crates/engine/src/game/scenario.rs
index 819c29200b..d9df01b955 100644
--- a/crates/engine/src/game/scenario.rs
+++ b/crates/engine/src/game/scenario.rs
@@ -1704,6 +1704,7 @@ impl GameRunner {
             WaitingFor::MulliganDecision { .. } => "MulliganDecision",
             WaitingFor::OpeningHandBottomCards { .. } => "OpeningHandBottomCards",
             WaitingFor::ManaPayment { .. } => "ManaPayment",
+            WaitingFor::ManaSourceSelection { .. } => "ManaSourceSelection",
             WaitingFor::TargetSelection { .. } => "TargetSelection",
             WaitingFor::DeclareAttackers { .. } => "DeclareAttackers",
             WaitingFor::DeclareBlockers { .. } => "DeclareBlockers",
@@ -2475,6 +2476,16 @@ impl<'a> SpellCast<'a> {
                     // CR 601.2h: finalize the (now fully convoke-paid) cost.
                     act_collect(runner, GameAction::PassPriority, &mut events)?;
                 }
+                WaitingFor::ManaSourceSelection { options, .. } => {
+                    let selection = options.first().cloned().unwrap_or_else(|| {
+                        panic!("ManaSourceSelection must offer at least one source")
+                    });
+                    act_collect(
+                        runner,
+                        GameAction::ActivateManaSource { selection },
+                        &mut events,
+                    )?;
+                }
                 // CR 601.2c: declare one target per slot, in written order.
                 WaitingFor::TargetSelection {
                     pending_cast,
@@ -2724,6 +2735,7 @@ fn waiting_for_variant_name(waiting: &WaitingFor) -> &'static str {
     // borrow-free match. Kept in sync with `GameRunner::waiting_for_kind`.
     match waiting {
         WaitingFor::ManaPayment { .. } => "ManaPayment",
+        WaitingFor::ManaSourceSelection { .. } => "ManaSourceSelection",
         WaitingFor::ChooseXValue { .. } => "ChooseXValue",
         WaitingFor::TargetSelection { .. } => "TargetSelection",
         WaitingFor::MultiTargetSelection { .. } => "MultiTargetSelection",
diff --git a/crates/engine/src/types/action_stable_order.rs b/crates/engine/src/types/action_stable_order.rs
index 27eb8c2719..016086f7a2 100644
--- a/crates/engine/src/types/action_stable_order.rs
+++ b/crates/engine/src/types/action_stable_order.rs
@@ -227,6 +227,18 @@ fn cmp_payload(a: &GameAction, b: &GameAction) -> Ordering {
             };
             a0.cmp_stable(b0)
         }
+        GameAction::ActivateManaSource { selection: a0 } => {
+            let GameAction::ActivateManaSource { selection: b0 } = b else {
+                unreachable!("cmp_payload: same-variant invariant");
+            };
+            a0.cmp_stable(b0)
+        }
+        GameAction::BackToManaPayment => {
+            let GameAction::BackToManaPayment = b else {
+                unreachable!("cmp_payload: same-variant invariant");
+            };
+            Ordering::Equal
+        }
         GameAction::UntapLandForMana { object_id: a0 } => {
             let GameAction::UntapLandForMana { object_id: b0 } = b else {
                 unreachable!("cmp_payload: same-variant invariant");
diff --git a/crates/engine/src/types/actions.rs b/crates/engine/src/types/actions.rs
index 42d795b702..aa8df815ea 100644
--- a/crates/engine/src/types/actions.rs
+++ b/crates/engine/src/types/actions.rs
@@ -256,6 +256,15 @@ pub enum GameAction {
     TapLandForMana {
         selection: ManaSourceSelection,
     },
+    /// CR 605.3a: Activate one exact engine-authored mana-source capability.
+    /// Unlike the legacy land-only action, this covers mana abilities on every
+    /// permanent type and preserves the selected output provenance.
+    ActivateManaSource {
+        selection: ManaSourceSelection,
+    },
+    /// Return from a sacrificial-mana choice to the exact saved payment state
+    /// without re-planning or mutating the mana pool.
+    BackToManaPayment,
     /// CR 605.3a: Undo a manual mana ability activation — untap source, remove produced mana.
     /// Only valid for lands in `lands_tapped_for_mana` whose mana hasn't been spent.
     UntapLandForMana {
@@ -1497,6 +1506,7 @@ impl GameAction {
         matches!(
             self,
             GameAction::TapLandForMana { .. }
+                | GameAction::ActivateManaSource { .. }
                 | GameAction::UntapLandForMana { .. }
                 // CR 118.3a: pinning/unpinning a pool unit is a mana-payment-window
                 // action; classifying it here keeps it out of AI priority-action
@@ -1551,6 +1561,7 @@ impl GameAction {
             | GameAction::CastSpellAsMadness { object_id, .. } => Some(*object_id),
             GameAction::ActivateAbility { source_id, .. } => Some(*source_id),
             GameAction::TapLandForMana { selection } => Some(selection.source.object_id),
+            GameAction::ActivateManaSource { selection } => Some(selection.source.object_id),
             GameAction::UntapLandForMana { object_id } => Some(*object_id),
             // CR 118.3a: act on a pool pip, not a battlefield object.
             GameAction::SpendPoolMana { .. } | GameAction::UnspendPoolMana { .. } => None,
@@ -1588,6 +1599,7 @@ impl GameAction {
             | GameAction::ChooseReplacement { .. }
             | GameAction::OrderTriggers { .. }
             | GameAction::CancelCast
+            | GameAction::BackToManaPayment
             | GameAction::SubmitSideboard { .. }
             | GameAction::ChoosePlayDraw { .. }
             | GameAction::ChooseOption { .. }
@@ -1870,6 +1882,9 @@ mod tests {
                         },
                         ability_index: None,
                         mana_type: crate::types::mana::ManaType::Green,
+                        output: crate::types::mana::ManaSourceOutput::Concrete(
+                            crate::types::mana::ManaType::Green,
+                        ),
                         atomic_combination: None,
                         restrictions: Vec::new(),
                         penalty: crate::types::mana::ManaSourcePenalty::None,
diff --git a/crates/engine/src/types/game_state.rs b/crates/engine/src/types/game_state.rs
index 14b04f9678..fb6eda280e 100644
--- a/crates/engine/src/types/game_state.rs
+++ b/crates/engine/src/types/game_state.rs
@@ -5352,6 +5352,10 @@ fn default_copy_retarget_effect_kind() -> EffectKind {
 pub enum CastPaymentMode {
     #[default]
     Auto,
+    /// CR 601.2g-h: auto-pay every safe mana row, but stop before an
+    /// activation whose cost sacrifices a permanent so its controller makes
+    /// that irreversible payment decision explicitly.
+    AutoExceptSacrificialMana,
     Manual,
 }
 
@@ -6138,6 +6142,16 @@ pub enum ManaAbilityResume {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         convoke_mode: Option<ConvokeMode>,
     },
+    /// CR 601.2g-h + CR 605.3b: automatic payment reached a mana source that
+    /// sacrifices a permanent. The options are the frozen, engine-authored
+    /// semantic capability snapshot; submission revalidates one exact current
+    /// candidate before it can mutate the payment.
+    ManaSourceSelection {
+        player: PlayerId,
+        options: Vec<crate::types::mana::ManaSourceSelection>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        convoke_mode: Option<ConvokeMode>,
+    },
     UnlessPayment {
         /// The player who owns the outer unless-payment poll. It can differ
         /// from the controller of a helper mana source activated while paying.
@@ -7705,6 +7719,16 @@ pub enum WaitingFor {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         convoke_mode: Option<ConvokeMode>,
     },
+    /// CR 601.2g-h + CR 605.3b: automatic payment reached a mana source that
+    /// sacrifices a permanent. The options are the frozen, engine-authored
+    /// semantic capability snapshot; submission revalidates one exact current
+    /// candidate before it can mutate the payment.
+    ManaSourceSelection {
+        player: PlayerId,
+        options: Vec<crate::types::mana::ManaSourceSelection>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        convoke_mode: Option<ConvokeMode>,
+    },
     /// CR 702.132a: Assist — when casting a spell with assist whose locked total
     /// cost has a generic component, before the caster pays they MAY choose
     /// another player to help pay the generic mana. The CASTER acts on this step
@@ -9838,6 +9862,7 @@ impl WaitingFor {
             WaitingFor::MulliganDecision { .. } => "MulliganDecision",
             WaitingFor::OpeningHandBottomCards { .. } => "OpeningHandBottomCards",
             WaitingFor::ManaPayment { .. } => "ManaPayment",
+            WaitingFor::ManaSourceSelection { .. } => "ManaSourceSelection",
             WaitingFor::ChooseXValue { .. } => "ChooseXValue",
             WaitingFor::TargetSelection { .. } => "TargetSelection",
             WaitingFor::DeclareAttackers { .. } => "DeclareAttackers",
@@ -9988,6 +10013,7 @@ impl WaitingFor {
             | WaitingFor::MeldPairChoice { player, .. }
             | WaitingFor::MeldAttackTargetChoice { player, .. }
             | WaitingFor::ManaPayment { player, .. }
+            | WaitingFor::ManaSourceSelection { player, .. }
             | WaitingFor::ChooseXValue { player, .. }
             | WaitingFor::TargetSelection { player, .. }
             | WaitingFor::DeclareAttackers { player, .. }
@@ -10148,12 +10174,13 @@ impl WaitingFor {
     ///
     /// Runtime drift detector: the `debug_assert!` in `game::derived` trips
     /// in tests if a new variant populates `GameState::pending_cast` without
-    /// being covered here (or by the `ManaPayment` exception in
+    /// being covered here (or by an external payment-state exception in
     /// `has_pending_cast`). That is the practical safeguard — the `_ => None`
     /// wildcard below does not compile-enforce variant coverage on its own.
     ///
-    /// Note: `ManaPayment` is the one casting-flow variant that does NOT embed
-    /// its `PendingCast`. It reads from `GameState::pending_cast` instead so
+    /// Note: `ManaPayment` and `ManaSourceSelection` are casting-flow variants
+    /// that do NOT embed their `PendingCast`. They read from
+    /// `GameState::pending_cast` instead so
     /// multiplayer visibility filtering (`game::visibility`) can clear
     /// mid-payment detail for opponents while preserving the public "spell on
     /// the stack" view elsewhere. `has_pending_cast()` accounts for this.
@@ -10228,8 +10255,8 @@ impl WaitingFor {
     /// Whether this state is part of the casting flow and can be backed out of
     /// with `CancelCast` (CR 601.2).
     ///
-    /// Derived from `pending_cast_ref()` plus the single `ManaPayment`
-    /// exception (which externalizes its `PendingCast` into
+    /// Derived from `pending_cast_ref()` plus the external payment states
+    /// (which externalize their `PendingCast` into
     /// `GameState::pending_cast`). Centralizing the predicate here guarantees
     /// that every variant carrying a `PendingCast` is covered — drift between
     /// data model and predicate is structurally prevented.
@@ -10243,9 +10270,18 @@ impl WaitingFor {
         self.pending_cast_ref().is_some()
             || matches!(
                 self,
-                WaitingFor::ManaPayment { .. } | WaitingFor::PhyrexianPayment { .. }
+                WaitingFor::ManaPayment { .. }
+                    | WaitingFor::ManaSourceSelection { .. }
+                    | WaitingFor::PhyrexianPayment { .. }
             )
     }
+
+    /// CR 601.2i: Whether the current prompt permits withdrawing the pending
+    /// spell. Kept distinct from `has_pending_cast`: a cast can be pending at
+    /// a mandatory choice without granting a cancellation action.
+    pub fn allows_cancel_cast(&self) -> bool {
+        self.has_pending_cast() && !matches!(self, WaitingFor::ManaSourceSelection { .. })
+    }
 }
 
 /// CR 102.1 + CR 500.1: which turn boundary ends an auto-pass session.
@@ -11482,6 +11518,11 @@ pub struct GameState {
     /// frontend doesn't need to maintain a parallel list of casting states.
     #[serde(skip_deserializing, default)]
     pub has_pending_cast: bool,
+    /// CR 601.2i: display-only authority for whether the current pending cast
+    /// may be withdrawn. Separate from `has_pending_cast` so choice prompts
+    /// can expose an in-flight cast without encouraging an illegal cancel.
+    #[serde(skip_deserializing, default)]
+    pub allows_cancel_cast: bool,
     pub lands_played_this_turn: u8,
     pub max_lands_per_turn: u8,
     pub priority_pass_count: u8,
@@ -16615,6 +16656,7 @@ impl GameState {
             next_interaction_serial: default_interaction_serial(),
             active_interaction_slots: Vec::new(),
             has_pending_cast: false,
+            allows_cancel_cast: false,
             lands_played_this_turn: 0,
             max_lands_per_turn: 1,
             priority_pass_count: 0,
@@ -18064,6 +18106,7 @@ fn _gamestate_partition_is_total(s: &GameState) {
         next_interaction_serial: _,
         active_interaction_slots: _,
         has_pending_cast: _,
+        allows_cancel_cast: _,
         lands_played_this_turn: _,
         max_lands_per_turn: _,
         priority_pass_count: _,
@@ -21409,6 +21452,11 @@ mod tests {
             player: PlayerId(0),
             convoke_mode: None,
         }));
+        variants.push(Box::new(WaitingFor::ManaSourceSelection {
+            player: PlayerId(0),
+            options: Vec::new(),
+            convoke_mode: None,
+        }));
         variants.push(Box::new(WaitingFor::DeclareAttackers {
             player: PlayerId(0),
             valid_attacker_ids: vec![],
@@ -21691,7 +21739,7 @@ mod tests {
             mana_reduction: ManaCost::zero(),
             pending_cast: dummy_pending(),
         }));
-        assert_eq!(variants.len(), 36);
+        assert_eq!(variants.len(), 37);
     }
 
     #[test]
@@ -21785,6 +21833,14 @@ mod tests {
         };
         assert!(mana_payment.pending_cast_ref().is_none());
         assert!(mana_payment.has_pending_cast());
+
+        let source_selection = WaitingFor::ManaSourceSelection {
+            player: PlayerId(0),
+            options: Vec::new(),
+            convoke_mode: None,
+        };
+        assert!(source_selection.has_pending_cast());
+        assert!(!source_selection.allows_cancel_cast());
     }
 
     #[test]
diff --git a/crates/engine/src/types/interaction.rs b/crates/engine/src/types/interaction.rs
index 830f083bb9..b26e041cd2 100644
--- a/crates/engine/src/types/interaction.rs
+++ b/crates/engine/src/types/interaction.rs
@@ -500,6 +500,8 @@ pub enum InteractionActionCode {
     MulliganDecision,
     ReorderHand,
     TapLandForMana,
+    ActivateManaSource,
+    BackToManaPayment,
     UntapLandForMana,
     SpendPoolMana,
     UnspendPoolMana,
diff --git a/crates/engine/src/types/mana.rs b/crates/engine/src/types/mana.rs
index be6749780d..515ae98c9d 100644
--- a/crates/engine/src/types/mana.rs
+++ b/crates/engine/src/types/mana.rs
@@ -669,6 +669,19 @@ pub enum ManaSourcePenalty {
     Sacrifices,
 }
 
+/// CR 106.1a: The output choice captured for a mana-source activation.
+///
+/// `Concrete` is the planner-selected output used by automatic payment. A
+/// manually selected flexible producer instead retains `DeferredColorChoice`,
+/// so the normal mana-choice interaction chooses its color at activation time
+/// rather than silently committing to an arbitrary planner row.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(tag = "type", content = "data")]
+pub enum ManaSourceOutput {
+    Concrete(ManaType),
+    DeferredColorChoice,
+}
+
 /// Exact identity of one triggered mana ability that augments a land's own
 /// production when that land is tapped for mana.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
@@ -678,24 +691,62 @@ pub struct TapsForManaSelection {
     pub production_override: ProductionOverride,
 }
 
-/// Stable semantic selection for one currently activatable land-mana row.
+/// Stable semantic selection for one currently activatable mana-source row.
 ///
 /// The action carries every field that can change legality or resolution, but
 /// the reducer never trusts those fields directly: it enumerates current live
 /// options and requires one exact semantic match before activating that live
 /// option. `ObjectIncarnationRef` prevents a stale choice from rebinding to an
 /// object that left and re-entered the battlefield (CR 400.7).
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
 pub struct ManaSourceSelection {
     pub source: ObjectIncarnationRef,
     pub ability_index: Option<usize>,
     pub mana_type: ManaType,
+    pub output: ManaSourceOutput,
     pub atomic_combination: Option<Vec<ManaType>>,
     pub restrictions: Vec<ManaRestriction>,
     pub penalty: ManaSourcePenalty,
     pub taps_for_mana: Vec<TapsForManaSelection>,
 }
 
+impl<'de> Deserialize<'de> for ManaSourceSelection {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        #[derive(Deserialize)]
+        struct WireSelection {
+            source: ObjectIncarnationRef,
+            ability_index: Option<usize>,
+            mana_type: ManaType,
+            #[serde(default)]
+            output: Option<ManaSourceOutput>,
+            atomic_combination: Option<Vec<ManaType>>,
+            restrictions: Vec<ManaRestriction>,
+            penalty: ManaSourcePenalty,
+            taps_for_mana: Vec<TapsForManaSelection>,
+        }
+
+        let wire = WireSelection::deserialize(deserializer)?;
+        Ok(Self {
+            source: wire.source,
+            ability_index: wire.ability_index,
+            mana_type: wire.mana_type,
+            // `TapLandForMana` actions saved before output provenance existed
+            // selected this exact row's `mana_type`; preserve that choice on
+            // replay instead of silently turning every old colored row colorless.
+            output: wire
+                .output
+                .unwrap_or(ManaSourceOutput::Concrete(wire.mana_type)),
+            atomic_combination: wire.atomic_combination,
+            restrictions: wire.restrictions,
+            penalty: wire.penalty,
+            taps_for_mana: wire.taps_for_mana,
+        })
+    }
+}
+
 impl ManaSourceSelection {
     /// Stable total order for the action wire. The non-`Ord` semantic fields
     /// are compared by explicit closed-enum comparators below; debug strings or
@@ -705,6 +756,7 @@ impl ManaSourceSelection {
             .cmp(&other.source)
             .then_with(|| self.ability_index.cmp(&other.ability_index))
             .then_with(|| self.mana_type.cmp(&other.mana_type))
+            .then_with(|| cmp_mana_source_output(self.output, other.output))
             .then_with(|| self.atomic_combination.cmp(&other.atomic_combination))
             .then_with(|| cmp_mana_restriction_slices(&self.restrictions, &other.restrictions))
             .then_with(|| cmp_mana_source_penalty(self.penalty, other.penalty))
@@ -712,6 +764,21 @@ impl ManaSourceSelection {
     }
 }
 
+fn cmp_mana_source_output(left: ManaSourceOutput, right: ManaSourceOutput) -> std::cmp::Ordering {
+    match (left, right) {
+        (ManaSourceOutput::Concrete(a), ManaSourceOutput::Concrete(b)) => a.cmp(&b),
+        (ManaSourceOutput::DeferredColorChoice, ManaSourceOutput::DeferredColorChoice) => {
+            std::cmp::Ordering::Equal
+        }
+        (ManaSourceOutput::Concrete(_), ManaSourceOutput::DeferredColorChoice) => {
+            std::cmp::Ordering::Less
+        }
+        (ManaSourceOutput::DeferredColorChoice, ManaSourceOutput::Concrete(_)) => {
+            std::cmp::Ordering::Greater
+        }
+    }
+}
+
 fn cmp_slice_by<T>(
     left: &[T],
     right: &[T],
diff --git a/crates/engine/src/types/mod.rs b/crates/engine/src/types/mod.rs
index 359b440d71..7e3c175c8b 100644
--- a/crates/engine/src/types/mod.rs
+++ b/crates/engine/src/types/mod.rs
@@ -63,8 +63,8 @@ pub use keywords::{Keyword, PartnerType, ProtectionTarget};
 pub use layers::{ActiveContinuousEffect, Layer};
 pub use log::{GameLogEntry, LogCategory, LogSegment};
 pub use mana::{
-    ManaColor, ManaCost, ManaCostShard, ManaPool, ManaRestriction, ManaSourcePenalty,
-    ManaSourceSelection, ManaType, ManaUnit, SpellMeta, TapsForManaSelection,
+    ManaColor, ManaCost, ManaCostShard, ManaPool, ManaRestriction, ManaSourceOutput,
+    ManaSourcePenalty, ManaSourceSelection, ManaType, ManaUnit, SpellMeta, TapsForManaSelection,
 };
 pub use match_config::{
     BetweenGamesPrompt, DeckCardCount, MatchConfig, MatchPhase, MatchScore, MatchType,
diff --git a/crates/engine/tests/fixtures/cr733/authority_matrix.json.gz b/crates/engine/tests/fixtures/cr733/authority_matrix.json.gz
index 3788c61d9d..e681f411b3 100644
Binary files a/crates/engine/tests/fixtures/cr733/authority_matrix.json.gz and b/crates/engine/tests/fixtures/cr733/authority_matrix.json.gz differ
diff --git a/crates/engine/tests/integration/main.rs b/crates/engine/tests/integration/main.rs
index 446cbd2097..f708b60fb3 100644
--- a/crates/engine/tests/integration/main.rs
+++ b/crates/engine/tests/integration/main.rs
@@ -1134,6 +1134,7 @@ mod s07_coiling_rebirth_full_cast;
 mod s07_create_token_sequence_middle;
 mod s07_malamet_castpath;
 mod s07_this_way_conditions;
+mod sacrificial_mana_choice;
 mod sakashima_of_a_thousand_faces_retains_other_abilities;
 mod same_is_true_type_statics;
 mod sandman_reanimate_self_and_land_s25;
diff --git a/crates/engine/tests/integration/sacrificial_mana_choice.rs b/crates/engine/tests/integration/sacrificial_mana_choice.rs
new file mode 100644
index 0000000000..12ef9a6510
--- /dev/null
+++ b/crates/engine/tests/integration/sacrificial_mana_choice.rs
@@ -0,0 +1,341 @@
+use engine::ai_support::candidate_actions;
+use engine::game::scenario::{GameRunner, GameScenario};
+use engine::types::ability::{
+    AbilityCost, AbilityDefinition, AbilityKind, Effect, ManaContribution, ManaProduction,
+    QuantityExpr, SacrificeCost, TargetFilter, TypeFilter, TypedFilter,
+};
+use engine::types::actions::GameAction;
+use engine::types::game_state::{CastPaymentMode, ManaChoice, PayCostKind, WaitingFor};
+use engine::types::identifiers::ObjectId;
+use engine::types::mana::{ManaColor, ManaCost, ManaType};
+use engine::types::phase::Phase;
+use engine::types::player::PlayerId;
+use engine::types::zones::Zone;
+
+const P0: PlayerId = PlayerId(0);
+
+fn sacrificial_mana_ability(cost: AbilityCost, color: ManaColor) -> AbilityDefinition {
+    AbilityDefinition::new(
+        AbilityKind::Activated,
+        Effect::Mana {
+            produced: ManaProduction::Fixed {
+                colors: vec![color],
+                contribution: ManaContribution::Base,
+            },
+            restrictions: vec![],
+            grants: vec![],
+            expiry: None,
+            target: None,
+        },
+    )
+    .cost(cost)
+}
+
+fn any_one_color_sacrificial_mana_ability(cost: AbilityCost) -> AbilityDefinition {
+    AbilityDefinition::new(
+        AbilityKind::Activated,
+        Effect::Mana {
+            produced: ManaProduction::AnyOneColor {
+                count: QuantityExpr::Fixed { value: 1 },
+                color_options: vec![ManaColor::Black, ManaColor::Red],
+                contribution: ManaContribution::Base,
+            },
+            restrictions: vec![],
+            grants: vec![],
+            expiry: None,
+            target: None,
+        },
+    )
+    .cost(cost)
+}
+
+fn begin_sacrificial_payment(runner: &mut GameRunner, spell: ObjectId) {
+    let card_id = runner.state().objects[&spell].card_id;
+    runner
+        .act(GameAction::CastSpell {
+            object_id: spell,
+            card_id,
+            targets: vec![],
+            payment_mode: CastPaymentMode::AutoExceptSacrificialMana,
+        })
+        .expect("the production cast path should stop before sacrificial mana");
+}
+
+fn offered_selection(
+    runner: &GameRunner,
+    source: ObjectId,
+) -> engine::types::mana::ManaSourceSelection {
+    let WaitingFor::ManaSourceSelection { options, .. } = &runner.state().waiting_for else {
+        panic!(
+            "expected sacrificial mana prompt from the cast path, got {:?}",
+            runner.state().waiting_for
+        );
+    };
+    options
+        .iter()
+        .find(|selection| selection.source.object_id == source)
+        .cloned()
+        .expect("the prompt should retain the sacrificial source's exact capability")
+}
+
+fn generic_spell(scenario: &mut GameScenario) -> ObjectId {
+    scenario
+        .add_spell_to_hand(P0, "Sacrificial Mana Payment Witness", true)
+        .with_mana_cost(ManaCost::generic(1))
+        .id()
+}
+
+/// A self-sacrificing mana ability is offered only after the real cast pipeline
+/// has exhausted non-sacrificial payment rows.
+#[test]
+fn self_sacrificing_mana_source_pays_a_production_cast() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Blood Pet Witness", 1, 1)
+        .with_ability_definition(sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(TargetFilter::SelfRef, 1)),
+            ManaColor::Black,
+        ))
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+    let selection = offered_selection(&runner, source);
+    runner
+        .act(GameAction::ActivateManaSource { selection })
+        .expect("the offered self-sacrificing source should activate during payment");
+
+    assert_eq!(runner.state().objects[&source].zone, Zone::Graveyard);
+    assert_eq!(
+        runner.state().players[P0.0 as usize]
+            .mana_pool
+            .count_color(ManaType::Black),
+        1,
+        "the activated source's mana reaches the pending spell payment"
+    );
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ManaPayment { .. }
+    ));
+
+    runner
+        .act(GameAction::PassPriority)
+        .expect("the selected mana should pay the spell through the ordinary payment reducer");
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::Priority { .. }
+    ));
+    assert_eq!(runner.state().objects[&spell].zone, Zone::Stack);
+}
+
+/// A frozen source selection must preserve an AnyOneColor activation's normal
+/// color prompt, then resume and finish the original cast.
+#[test]
+fn any_one_color_self_sacrifice_selection_completes_production_cast() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Gold Witness", 1, 1)
+        .with_ability_definition(any_one_color_sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(TargetFilter::SelfRef, 1)),
+        ))
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+    let selection = offered_selection(&runner, source);
+    runner
+        .act(GameAction::ActivateManaSource { selection })
+        .expect("the frozen self-sacrifice selection should enter the color prompt");
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ChooseManaColor { .. }
+    ));
+
+    runner
+        .act(GameAction::ChooseManaColor {
+            choice: ManaChoice::SingleColor(ManaType::Red),
+            count: 1,
+        })
+        .expect("choosing the source's color should resume the pending payment");
+    assert_eq!(runner.state().objects[&source].zone, Zone::Graveyard);
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ManaPayment { .. }
+    ));
+
+    runner
+        .act(GameAction::PassPriority)
+        .expect("the chosen mana should finish the original cast");
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::Priority { .. }
+    ));
+    assert_eq!(runner.state().objects[&spell].zone, Zone::Stack);
+}
+
+/// A non-sacrificial row on the same permanent remains available to the
+/// automatic planner; only the irreversible row is held for explicit consent.
+#[test]
+fn automatic_payment_keeps_a_non_sacrificial_row_on_a_sacrificial_source() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Two-Row Mana Witness", 1, 1)
+        .as_artifact()
+        .with_ability_definition(sacrificial_mana_ability(AbilityCost::Tap, ManaColor::Red))
+        .with_ability_definition(sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(TargetFilter::SelfRef, 1)),
+            ManaColor::Black,
+        ))
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::Priority { .. }
+    ));
+    assert!(runner.state().objects[&source].tapped);
+    assert_eq!(runner.state().objects[&source].zone, Zone::Battlefield);
+    assert_eq!(runner.state().objects[&spell].zone, Zone::Stack);
+}
+
+/// The pre-activation prompt does not bypass a mana ability's own sacrifice
+/// choice; selecting another artifact pays that cost while its source remains
+/// on the battlefield.
+#[test]
+fn sacrifice_another_permanent_mana_source_resumes_the_pending_cast() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Krark-Clan Ironworks Witness", 1, 1)
+        .as_artifact()
+        .with_ability_definition(sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(
+                TargetFilter::Typed(TypedFilter::new(TypeFilter::Artifact)),
+                1,
+            )),
+            ManaColor::Red,
+        ))
+        .id();
+    let sacrifice = scenario
+        .add_creature(P0, "Sacrificial Artifact Witness", 1, 1)
+        .as_artifact()
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+    let selection = offered_selection(&runner, source);
+    runner
+        .act(GameAction::ActivateManaSource { selection })
+        .expect("the offered source should enter its normal interactive cost payment");
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::PayCost {
+            kind: PayCostKind::Sacrifice,
+            ref choices,
+            ..
+        } if choices.contains(&sacrifice)
+    ));
+
+    runner
+        .act(GameAction::SelectCards {
+            cards: vec![sacrifice],
+        })
+        .expect("the source's ordinary sacrifice-cost reducer should accept another artifact");
+
+    assert_eq!(runner.state().objects[&source].zone, Zone::Battlefield);
+    assert_eq!(runner.state().objects[&sacrifice].zone, Zone::Graveyard);
+    assert_eq!(
+        runner.state().players[P0.0 as usize].mana_pool.total(),
+        1,
+        "the selected ability's mana remains available to the original spell"
+    );
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ManaPayment { .. }
+    ));
+}
+
+/// Returning from the safety prompt keeps the pending spell but neither spends
+/// mana nor performs the irreversible source activation.
+#[test]
+fn back_from_sacrificial_mana_prompt_preserves_the_cast_without_cancellation() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Back Button Witness", 1, 1)
+        .with_ability_definition(sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(TargetFilter::SelfRef, 1)),
+            ManaColor::Black,
+        ))
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+    assert!(
+        !candidate_actions(runner.state())
+            .iter()
+            .any(|candidate| matches!(candidate.action, GameAction::CancelCast)),
+        "the real safety prompt must not synthesize a cast-cancellation action"
+    );
+    runner
+        .act(GameAction::BackToManaPayment)
+        .expect("the prompt's explicit back action should be accepted");
+
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ManaPayment { .. }
+    ));
+    assert!(runner.state().pending_cast.is_some());
+    assert_eq!(runner.state().objects[&source].zone, Zone::Battlefield);
+    assert_eq!(runner.state().players[P0.0 as usize].mana_pool.total(), 0);
+}
+
+/// An engine-authored selection is revalidated at the reducer boundary, so a
+/// source that became ineligible cannot be activated from a stale payment prompt.
+#[test]
+fn stale_sacrificial_mana_selection_is_rejected_without_mutating_payment() {
+    let mut scenario = GameScenario::new();
+    scenario.at_phase(Phase::PreCombatMain);
+    let spell = generic_spell(&mut scenario);
+    let source = scenario
+        .add_creature(P0, "Stale Selection Witness", 1, 1)
+        .with_ability_definition(sacrificial_mana_ability(
+            AbilityCost::Sacrifice(SacrificeCost::count(TargetFilter::SelfRef, 1)),
+            ManaColor::Black,
+        ))
+        .id();
+    let mut runner = scenario.build();
+
+    begin_sacrificial_payment(&mut runner, spell);
+    let selection = offered_selection(&runner, source);
+    runner
+        .state_mut()
+        .objects
+        .get_mut(&source)
+        .unwrap()
+        .controller = PlayerId(1);
+
+    assert!(
+        runner
+            .act(GameAction::ActivateManaSource { selection })
+            .is_err(),
+        "a stale source must fail before the payment reducer mutates state"
+    );
+    assert!(matches!(
+        runner.state().waiting_for,
+        WaitingFor::ManaSourceSelection { .. }
+    ));
+    assert_eq!(runner.state().objects[&source].zone, Zone::Battlefield);
+    assert_eq!(runner.state().objects[&source].controller, PlayerId(1));
+    assert_eq!(runner.state().players[P0.0 as usize].mana_pool.total(), 0);
+}
diff --git a/crates/manabrew-compat/src/lib.rs b/crates/manabrew-compat/src/lib.rs
index 4651f4588c..8fa9ce7fe8 100644
--- a/crates/manabrew-compat/src/lib.rs
+++ b/crates/manabrew-compat/src/lib.rs
@@ -2545,7 +2545,7 @@ pub fn convert_available_action(
                 produced_mana: None,
             }),
         }),
-        GameAction::TapLandForMana { selection } => {
+        GameAction::TapLandForMana { selection } | GameAction::ActivateManaSource { selection } => {
             AvailableActionConversion::Available(AvailableAction {
                 id,
                 kind: AvailableActionKind::ActivateAbility(ActivatableAbilityInfo {
@@ -2567,9 +2567,10 @@ pub fn convert_available_action(
                 },
             })
         }
-        GameAction::PassPriority | GameAction::CancelCast | GameAction::Concede { .. } => {
-            AvailableActionConversion::Skip
-        }
+        GameAction::PassPriority
+        | GameAction::CancelCast
+        | GameAction::BackToManaPayment
+        | GameAction::Concede { .. } => AvailableActionConversion::Skip,
         GameAction::DeclareAttackers { .. } => AvailableActionConversion::Skip,
         GameAction::DeclareBlockers { .. } => AvailableActionConversion::Skip,
         GameAction::ChooseUntap { .. } => {
diff --git a/crates/phase-ai/src/decision_kind.rs b/crates/phase-ai/src/decision_kind.rs
index 7b9d1b7e5d..82ad9727e2 100644
--- a/crates/phase-ai/src/decision_kind.rs
+++ b/crates/phase-ai/src/decision_kind.rs
@@ -20,7 +20,9 @@ pub fn classify(waiting_for: &WaitingFor, action: &GameAction) -> DecisionKind {
         WaitingFor::MulliganDecision { .. } | WaitingFor::OpeningHandBottomCards { .. } => {
             DecisionKind::Mulligan
         }
-        WaitingFor::ManaPayment { .. } | WaitingFor::PhyrexianPayment { .. } => {
+        WaitingFor::ManaPayment { .. }
+        | WaitingFor::ManaSourceSelection { .. }
+        | WaitingFor::PhyrexianPayment { .. } => {
             DecisionKind::ManaPayment
         }
         WaitingFor::ChooseXValue { .. } => DecisionKind::ChooseX,
@@ -58,7 +60,9 @@ pub fn classify(waiting_for: &WaitingFor, action: &GameAction) -> DecisionKind {
             GameAction::PlayLand { .. } => DecisionKind::PlayLand,
             GameAction::CastSpell { .. } => DecisionKind::CastSpell,
             GameAction::ActivateAbility { .. } => DecisionKind::ActivateAbility,
-            GameAction::TapLandForMana { .. } | GameAction::UntapLandForMana { .. } => {
+            GameAction::TapLandForMana { .. }
+            | GameAction::ActivateManaSource { .. }
+            | GameAction::UntapLandForMana { .. } => {
                 DecisionKind::ActivateManaAbility
             }
             // Default: any other priority-time action (PassPriority, special
@@ -338,6 +342,9 @@ mod tests {
                         },
                         ability_index: None,
                         mana_type: engine::types::mana::ManaType::Green,
+                        output: engine::types::mana::ManaSourceOutput::Concrete(
+                            engine::types::mana::ManaType::Green,
+                        ),
                         atomic_combination: None,
                         restrictions: Vec::new(),
                         penalty: engine::types::mana::ManaSourcePenalty::None,
diff --git a/crates/phase-ai/src/policies/discard_payoff.rs b/crates/phase-ai/src/policies/discard_payoff.rs
index 0330d1909a..8e409884a7 100644
--- a/crates/phase-ai/src/policies/discard_payoff.rs
+++ b/crates/phase-ai/src/policies/discard_payoff.rs
@@ -198,6 +198,8 @@ fn candidate_discards_controller(ctx: &PolicyContext<'_>) -> bool {
         | GameAction::MulliganDecision { .. }
         | GameAction::ReorderHand { .. }
         | GameAction::TapLandForMana { .. }
+        | GameAction::ActivateManaSource { .. }
+        | GameAction::BackToManaPayment
         | GameAction::UntapLandForMana { .. }
         | GameAction::SpendPoolMana { .. }
         | GameAction::UnspendPoolMana { .. }
diff --git a/crates/phase-ai/src/policies/draw_payoff.rs b/crates/phase-ai/src/policies/draw_payoff.rs
index 1523e59c75..bd3c2d682a 100644
--- a/crates/phase-ai/src/policies/draw_payoff.rs
+++ b/crates/phase-ai/src/policies/draw_payoff.rs
@@ -225,6 +225,8 @@ fn candidate_draws_structurally(ctx: &PolicyContext<'_>) -> bool {
         | GameAction::MulliganDecision { .. }
         | GameAction::ReorderHand { .. }
         | GameAction::TapLandForMana { .. }
+        | GameAction::ActivateManaSource { .. }
+        | GameAction::BackToManaPayment
         | GameAction::UntapLandForMana { .. }
         | GameAction::SpendPoolMana { .. }
         | GameAction::UnspendPoolMana { .. }
diff --git a/crates/phase-ai/src/search.rs b/crates/phase-ai/src/search.rs
index fc84ed5f34..70bba9440e 100644
--- a/crates/phase-ai/src/search.rs
+++ b/crates/phase-ai/src/search.rs
@@ -767,6 +767,19 @@ pub fn emit_trace_for_candidate(
 /// `config` supplies policy penalties used by selection escapes (e.g. sacrifice
 /// value ordering); difficulty/search knobs are unused here.
 pub fn fallback_action(state: &GameState, config: &AiConfig) -> Option<GameAction> {
+    // CR 605.3b: A sacrificial mana prompt is an explicit payment decision,
+    // not a generic pending-cast failure. Pick only an engine-issued source or
+    // the exact BackToManaPayment escape; never synthesize CancelCast here.
+    if matches!(state.waiting_for, WaitingFor::ManaSourceSelection { .. }) {
+        return engine::ai_support::legal_actions(state)
+            .into_iter()
+            .find(|action| {
+                matches!(
+                    action,
+                    GameAction::ActivateManaSource { .. } | GameAction::BackToManaPayment
+                )
+            });
+    }
     // CR 601.2c: A spell's target step must use the engine's current legal
     // target list. `target_slots` is a historical snapshot and can be stale
     // after earlier selections; if no current legal action remains, abort the
@@ -781,7 +794,11 @@ pub fn fallback_action(state: &GameState, config: &AiConfig) -> Option<GameActio
     // Pending-cast states can always be escaped with CancelCast (CR 601.2).
     // Check this before the exhaustive match so every pending-cast variant
     // is covered without repeating CancelCast per-arm.
-    if state.waiting_for.has_pending_cast() {
+    if state.waiting_for.allows_cancel_cast()
+        || state.allows_cancel_cast
+        || (matches!(state.waiting_for, WaitingFor::DistributeAmong { .. })
+            && state.pending_cast.is_some())
+    {
         // The internal discriminant tag is niche-optimized (non-sequential), so
         // print the variant *name* (the Debug prefix before its first field) and
         // the in-flight spell's card name instead — an opaque discriminant alone
@@ -1747,6 +1764,7 @@ pub fn fallback_action(state: &GameState, config: &AiConfig) -> Option<GameActio
         // guard above. This arm is structurally unreachable but required
         // for exhaustive match. ManaPayment is a pending-cast state.
         WaitingFor::ManaPayment { .. }
+        | WaitingFor::ManaSourceSelection { .. }
         | WaitingFor::OptionalCostChoice { .. }
         | WaitingFor::SpliceOffer { .. }
         | WaitingFor::DefilerPayment { .. }
@@ -1759,8 +1777,9 @@ pub fn fallback_action(state: &GameState, config: &AiConfig) -> Option<GameActio
         | WaitingFor::CollectEvidenceChoice { .. }
         | WaitingFor::HarmonizeTapChoice { .. } => {
             // These are all pending-cast states — the has_pending_cast guard
-            // above already returned CancelCast. This branch is unreachable
-            // at runtime but keeps the match exhaustive.
+            // above already returned CancelCast. ManaSourceSelection is
+            // intercepted above and never synthesizes CancelCast. This branch
+            // is unreachable at runtime but keeps the match exhaustive.
             Some(GameAction::CancelCast)
         }
     }
diff --git a/crates/server-core/src/client_message_wire_guard.rs b/crates/server-core/src/client_message_wire_guard.rs
index b66fc9f433..3fe9c116f4 100644
--- a/crates/server-core/src/client_message_wire_guard.rs
+++ b/crates/server-core/src/client_message_wire_guard.rs
@@ -304,6 +304,7 @@ mod tests {
                     source: ObjectIncarnationRef::of(ObjectId(1), 1),
                     ability_index: None,
                     mana_type: ManaType::Green,
+                    output: engine::types::mana::ManaSourceOutput::Concrete(ManaType::Green),
                     atomic_combination: None,
                     restrictions: vec![ManaRestriction::OnlyForAny(vec![
                         ManaRestriction::OnlyForSpell;
@@ -328,6 +329,7 @@ mod tests {
                     source: ObjectIncarnationRef::of(ObjectId(1), 1),
                     ability_index: None,
                     mana_type: ManaType::Green,
+                    output: engine::types::mana::ManaSourceOutput::Concrete(ManaType::Green),
                     atomic_combination: None,
                     restrictions: Vec::new(),
                     penalty: ManaSourcePenalty::None,
diff --git a/crates/server-core/src/game_action_payload_guard.rs b/crates/server-core/src/game_action_payload_guard.rs
index 29442cfc55..5844a3c693 100644
--- a/crates/server-core/src/game_action_payload_guard.rs
+++ b/crates/server-core/src/game_action_payload_guard.rs
@@ -565,7 +565,7 @@ pub fn guard_game_action_payload(action: &GameAction) -> Result<(), String> {
             bound_list("SetPhaseStops.stops", stops.len())?;
         }
         GameAction::SetPriorityPassingMode { .. } => {}
-        GameAction::TapLandForMana { selection } => {
+        GameAction::TapLandForMana { selection } | GameAction::ActivateManaSource { selection } => {
             guard_mana_source_selection_payload(selection)?;
         }
         GameAction::DistributeAmong { distribution, .. } => {
@@ -618,6 +618,7 @@ pub fn guard_game_action_payload(action: &GameAction) -> Result<(), String> {
         | GameAction::ChooseAssistPlayer { .. }
         | GameAction::CommitAssistPayment { .. }
         | GameAction::MulliganDecision { .. }
+        | GameAction::BackToManaPayment
         | GameAction::UntapLandForMana { .. }
         | GameAction::SpendPoolMana { .. }
         | GameAction::UnspendPoolMana { .. }
diff --git a/crates/server-core/src/protocol.rs b/crates/server-core/src/protocol.rs
index ea2b06b7a0..4e9069a6f0 100644
--- a/crates/server-core/src/protocol.rs
+++ b/crates/server-core/src/protocol.rs
@@ -627,6 +627,7 @@ mod tests {
                 source: ObjectIncarnationRef::of(ObjectId(7), 3),
                 ability_index: None,
                 mana_type: ManaType::Green,
+                output: engine::types::mana::ManaSourceOutput::Concrete(ManaType::Green),
                 atomic_combination: None,
                 restrictions: Vec::new(),
                 penalty: ManaSourcePenalty::None,
@@ -653,6 +654,22 @@ mod tests {
             }
             _ => panic!("wrong variant"),
         }
+
+        let GameAction::TapLandForMana { selection } = action else {
+            unreachable!("fixture action is a land-mana selection");
+        };
+        let generic = GameAction::ActivateManaSource { selection };
+        let json = serde_json::to_string(&ClientMessage::Action {
+            action: generic.clone(),
+        })
+        .unwrap();
+        let parsed: ClientMessage = serde_json::from_str(&json).unwrap();
+        match parsed {
+            ClientMessage::Action {
+                action: restored_action,
+            } => assert_eq!(restored_action, generic),
+            _ => panic!("wrong variant"),
+        }
     }
 
     #[test]
diff --git a/crates/server-core/tests/game_action_payload_guard.rs b/crates/server-core/tests/game_action_payload_guard.rs
index 5a2c77fc86..9aa6d4bfe6 100644
--- a/crates/server-core/tests/game_action_payload_guard.rs
+++ b/crates/server-core/tests/game_action_payload_guard.rs
@@ -31,6 +31,7 @@ fn mana_source_selection() -> ManaSourceSelection {
         source: ObjectIncarnationRef::of(ObjectId(1), 1),
         ability_index: Some(0),
         mana_type: ManaType::Green,
+        output: engine::types::mana::ManaSourceOutput::Concrete(ManaType::Green),
         atomic_combination: None,
         restrictions: Vec::new(),
         penalty: ManaSourcePenalty::None,