Monsters ride the wormhole; mental force fails loudly (rules rev 5)

Two findings from the first human-vs-Claude duel (room 9UA6). A
creature standing on a DIMENSIONAL WARP token had no way through it —
warpStep obeys only wizards. The new creatureWarpStep command steps a
commanded creature through the tokens under the walker's rules: one
move spent, solid stone refuses it, FEAR holds the beast, touch
effects greet whoever shares the landing; the board taps the paired
token like a rim mouth. Replay-safe ungated — a new command widens
nothing that was recorded.

MENTAL FORCE ate its card silently when the destination lay beyond
the victim's three walked spaces — the caster spent an attack and
learned nothing (ask me how I know). Rev 5 refuses the impossible
destination up front with the card kept; when the victim slips out of
range between cast and resolution, a mentalForceFizzled event tells
the table what happened instead of nothing. All 20 production ledgers
verified, the duel's own among them; 283 tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015RCWSTnb1KYTPyL4GmhGnF

packages/engine/src/game.ts

@@ -226,7 +226,7 @@ export interface CastParams {
 }
 
 /** The revision new games are dealt under; GameConfig.deckRev pins it per game. */
-export const CURRENT_RULES_REV = 4;
+export const CURRENT_RULES_REV = 5;
 
 export interface GameConfig {
   playerIds: PlayerId[];
@@ -248,6 +248,8 @@ export interface GameConfig {
    * Rev 4: "the door will relock behind you" means it — passing through
    * an unlocked door shuts it at the walker's back unless a hand holds
    * it; unpassed, it relocks at turn's end as before.
+   * Rev 5: MENTAL FORCE refuses a destination the victim cannot walk to
+   * in three spaces, instead of eating the card silently at resolution.
    */
   deckRev?: number;
 }
@@ -579,6 +581,8 @@ export type GameEvent =
   | { type: "illusionWallCreated"; caster: PlayerId; edge: { cell: Cell; side: Side } }
   | { type: "illusionTested"; player: PlayerId; edge: string; result: "believes" | "seesThrough" }
   | { type: "sectorRotated"; caster: PlayerId; sectorIndex: number; clockwise: boolean }
+  | { type: "creatureWarpStepped"; creatureId: string; from: Cell; to: Cell; by: PlayerId }
+  | { type: "mentalForceFizzled"; attacker: PlayerId; defender: PlayerId; cell: Cell }
   | { type: "sectorRelocated"; caster: PlayerId; sectorIndex: number; from: Cell; to: Cell;
       /** Origins in FINAL coordinates (the maze may renormalize after the
        * landing); from/to record the pre-shift request. */
@@ -695,6 +699,7 @@ export type Command =
   | { type: "wardChoice"; play: boolean }
   | { type: "warpStep" }
   | { type: "moveCreature"; creatureId: string; direction: Side }
+  | { type: "creatureWarpStep"; creatureId: string }
   | { type: "creatureAttack"; creatureId: string; targetId: string }
   | {
       type: "cast";
@@ -747,7 +752,7 @@ type AttackEffect = {
   sustains?: boolean;
   /** Card stays in hand and is displayed rather than discarded (WIZARDBLADE). */
   keepInHand?: boolean;
-  validate?: (state: GameState, cmd: Extract<Command, { type: "cast" }>) => string | null;
+  validate?: (state: GameState, cmd: Extract<Command, { type: "cast" }>, caster?: PlayerState, target?: PlayerState) => string | null;
   onResolved?: (ctx: ResolutionContext) => void;
 };
 
@@ -2163,11 +2168,19 @@ const CARD_EFFECTS: Record<string, AttackEffect | NeutralEffect | CounterEffect>
   "mental-force": {
     kind: "attack",
     baseDamage: () => 0, // no LOS printed
-    validate: (state, cmd) => {
+    validate: (state, cmd, caster, target) => {
       const cell = cmd.params?.cell;
       if (!cell) return "say where they go (within three moved spaces)";
       if (!boardView(state).cells[cellKey(cell)]) return "off the board";
       if (state.squareContents[cellKey(cell)]?.kind === "stone") return "that square is solid stone";
+      // The victim WALKS those three spaces — a destination the maze's
+      // walls put out of reach is refused up front, not swallowed at
+      // resolution with the card already spent. (Rev 5; the victim may
+      // still slip out of range before it resolves — see onResolved.)
+      if ((state.config.deckRev ?? 1) >= 5 && target &&
+          walkingDistance(state, target.position, cell) > 3) {
+        return "the walls put that square beyond three moved spaces";
+      }
       return null;
     },
     onResolved: (ctx) => {
@@ -2175,7 +2188,12 @@ const CARD_EFFECTS: Record<string, AttackEffect | NeutralEffect | CounterEffect>
       if (isLockedInPlace(ctx.state, ctx.defender.id)) return;
       const to = ctx.stack.params?.cell;
       if (!to) return; // an ambush armed without a destination fizzles
-      if (walkingDistance(ctx.state, ctx.defender.position, to) > 3) return;
+      if (walkingDistance(ctx.state, ctx.defender.position, to) > 3) {
+        // The victim slipped beyond reach: the force strains and fails,
+        // and the table sees it fail rather than wondering.
+        ctx.events.push({ type: "mentalForceFizzled", attacker: ctx.attacker.id, defender: ctx.defender.id, cell: to });
+        return;
+      }
       const from = ctx.defender.position;
       ctx.defender.position = to;
       ctx.events.push({ type: "teleported", player: ctx.defender.id, from, to, by: ctx.attacker.id, cardId: "mental-force" });
@@ -2920,6 +2938,57 @@ function impCheck(state: GameState, events: GameEvent[], onlyPlayer?: PlayerId):
   checkVictory(state, events);
 }
 
+/** A creature standing on a DIMENSIONAL WARP token steps through it like
+ * any walker: its commander spends one of its moves, solid stone on the
+ * far side refuses it, and a monster is no braver than a wizard about
+ * FEAR. (Monsters obey the same maze the wizards do.) */
+function doCreatureWarpStep(prev: GameState, creatureId: string): CommandResult {
+  const blocked = requireActionsAvailable(prev);
+  if (blocked) return err(blocked);
+  const state = clone(prev);
+  const active = activePlayer(state);
+  const creature = creatureById(state, creatureId);
+  if (!creature) return err("no such creature");
+  if (creature.kind !== "democratic-monster" && creature.controllerId !== active.id) {
+    return err("that creature does not obey you");
+  }
+  if (creature.movesPerTurn === 0) return err("that creature cannot move");
+  if (creature.movementUsed >= creature.movesPerTurn) return err("no creature movement left");
+  const here = cellKey(creature.position);
+  const pair = state.dimWarps.find((w) => cellKey(w.a) === here || cellKey(w.b) === here);
+  if (!pair) return err("it is not standing on a warp token");
+  const dest = cellKey(pair.a) === here ? pair.b : pair.a;
+  if (state.squareContents[cellKey(dest)]?.kind === "stone") return err("the far side is solid stone");
+  if (state.players.some((o) => o.alive && cellKey(o.position) === cellKey(dest) &&
+        sustainedOn(state, o.id, "big-man").length > 0)) {
+    return err("a giant fills that square");
+  }
+  const from = creature.position;
+  // FEAR holds monsters off too: "no player or monster".
+  if (fearRepels(state, null, from, dest)) return err("an unnatural dread stops the beast");
+  creature.position = { ...dest };
+  creature.movementUsed++;
+  const events: GameEvent[] = [{ type: "creatureWarpStepped", creatureId, from, to: creature.position, by: active.id }];
+  // Touch effects on arriving in a player's square, as any step has.
+  for (const p of state.players) {
+    if (!p.alive || cellKey(p.position) !== cellKey(creature.position)) continue;
+    if (p.id === creature.controllerId && creature.kind !== "democratic-monster") continue;
+    if (creature.kind === "wraith" && !creature.attackUsed) {
+      creature.attackUsed = true;
+      events.push({ type: "creatureTouched", creatureId: creature.id, kind: creature.kind, player: p.id });
+      openCreatureStack(state, creature, p, 2, "wraith");
+      return { ok: true, state, events };
+    }
+    if (creature.kind === "democratic-monster" && !creature.attackUsed && !creature.justCreated) {
+      creature.attackUsed = true;
+      events.push({ type: "creatureTouched", creatureId: creature.id, kind: creature.kind, player: p.id });
+      openCreatureStack(state, creature, p, 2, "claw");
+      return { ok: true, state, events };
+    }
+  }
+  return { ok: true, state, events };
+}
+
 function doMoveCreature(prev: GameState, creatureId: string, direction: Side): CommandResult {
   const blocked = requireActionsAvailable(prev);
   if (blocked) return err(blocked);
@@ -3739,6 +3808,7 @@ function applyCommandInner(state: GameState, playerId: PlayerId, command: Comman
     case "wardChoice": return err("no grab is hanging on your Ward");
     case "warpStep": return doWarpStep(state);
     case "moveCreature": return doMoveCreature(state, command.creatureId, command.direction);
+    case "creatureWarpStep": return doCreatureWarpStep(state, command.creatureId);
     case "creatureAttack": return doCreatureAttack(state, command.creatureId, command.targetId);
     case "cast": return doCast(state, command);
     case "setAmbush": return doSetAmbush(state, command);
@@ -5006,7 +5076,7 @@ function doCast(prev: GameState, cmd: Extract<Command, { type: "cast" }>): Comma
       (s) => !(s.cardId === "buddy" && s.casterId === caster.id && s.targetId === target.id),
     );
     if (effect.validate) {
-      const problem = effect.validate(state, cmd);
+      const problem = effect.validate(state, cmd, caster, target);
       if (problem) return err(problem);
     }
     if (inHand.cardId === "waterbolt") {

packages/engine/test/casting.test.ts

@@ -1140,3 +1140,29 @@ describe("stone dead counts only the stones in play", () => {
     expect(state.players.find((p) => p.id === defender)!.life).toBe(12);
   });
 });
+
+describe("MENTAL FORCE respects the victim's three walked spaces", () => {
+  it("a destination beyond the walls is refused up front, card kept", () => {
+    let { state } = newGame();
+    state = toRound2(state);
+    const caster = activePlayer(state);
+    const victim = state.players.find((p) => p.id !== caster.id)!;
+    caster.position = { x: 0, y: 0 };
+    victim.position = { x: 2, y: 4 };
+    // Seal the victim into their square: every walked space is out of
+    // reach, so ANY other destination is beyond three moved spaces.
+    for (const side of SIDES) {
+      state.edgeOverrides[edgeKey(victim.position, side)] = "wall";
+    }
+    const mf = giveCard(state, caster.id, "mental-force", "MF");
+    const far = { x: 4, y: 9 };
+    const refused = applyCommand(state, caster.id, {
+      type: "cast", instanceId: mf.instanceId,
+      target: { kind: "player", playerId: victim.id }, params: { cell: far },
+    });
+    expect(refused.ok).toBe(false);
+    if (!refused.ok) expect(refused.error).toContain("three moved spaces");
+    // The card is still in hand — nothing was spent on the refusal.
+    expect(state.players.find((p) => p.id === caster.id)!.hand.some((c) => c.instanceId === mf.instanceId)).toBe(true);
+  });
+});

packages/engine/test/creatures.test.ts

@@ -752,3 +752,38 @@ describe("fear holds off monsters and unwilling feet alike", () => {
     expect(r.ok).toBe(true);
   });
 });
+
+describe("creatures and the dimensional warp", () => {
+  it("a commanded troll steps through the warp tokens", () => {
+    let { state } = createGame({ playerIds: ["a", "b"], seed: 42, sets: ["basic", "expansion1"] });
+    const you = state.players[state.turn.activeIndex]!.id;
+    state.dimWarps.push({ a: { x: 1, y: 1 }, b: { x: 3, y: 8 } });
+    state.creatures.push({
+      id: "troll-w", kind: "troll", controllerId: you, position: { x: 1, y: 1 },
+      life: 6, movesPerTurn: 2, movementUsed: 0, attackUsed: false,
+      justCreated: false, wallPassesPerTurn: 0, wallPassUsed: 0,
+    } as never);
+    const r = applyCommand(state, you, { type: "creatureWarpStep", creatureId: "troll-w" });
+    expect(r.ok).toBe(true);
+    if (r.ok) {
+      const troll = r.state.creatures.find((c) => c.id === "troll-w")!;
+      expect(cellKey(troll.position)).toBe(cellKey({ x: 3, y: 8 }));
+      expect(troll.movementUsed).toBe(1);
+    }
+  });
+
+  it("solid stone on the far side refuses the beast", () => {
+    let { state } = createGame({ playerIds: ["a", "b"], seed: 42, sets: ["basic", "expansion1"] });
+    const you = state.players[state.turn.activeIndex]!.id;
+    state.dimWarps.push({ a: { x: 1, y: 1 }, b: { x: 3, y: 8 } });
+    state.squareContents[cellKey({ x: 3, y: 8 })] = { kind: "stone", damage: 0, createdBy: "b" };
+    state.creatures.push({
+      id: "troll-w", kind: "troll", controllerId: you, position: { x: 1, y: 1 },
+      life: 6, movesPerTurn: 2, movementUsed: 0, attackUsed: false,
+      justCreated: false, wallPassesPerTurn: 0, wallPassUsed: 0,
+    } as never);
+    const r = applyCommand(state, you, { type: "creatureWarpStep", creatureId: "troll-w" });
+    expect(r.ok).toBe(false);
+    if (!r.ok) expect(r.error).toContain("stone");
+  });
+});