diff --git a/packages/engine/src/game.ts b/packages/engine/src/game.ts
index cb78dd9..cb9b60b 100644
--- a/packages/engine/src/game.ts
+++ b/packages/engine/src/game.ts
@@ -238,7 +238,7 @@ export interface CastParams {
 }
 
 /** The revision new games are dealt under; GameConfig.deckRev pins it per game. */
-export const CURRENT_RULES_REV = 15;
+export const CURRENT_RULES_REV = 16;
 
 /** Every rulings revision since the baseline, newest last — the entries a
  * game's deckRev freezes it before or after. Shown to players as the house
@@ -258,6 +258,7 @@ export const RULES_REVISIONS: { rev: number; note: string }[] = [
   { rev: 13, note: "SLOW DEATH's per-draw bites land as ONE blow that pauses for a victim holding ABSORB or BLUNT — countered against the total (absorb soaks up to 3, blunt halves rounding up); older games bit instantly." },
   { rev: 14, note: "Crossing a pit on a 2, 3, or 4 means edging around its rim: the walker lands on an open square beside the pit — the only one if there is one, otherwise the one they name by clicking it — and a pit with no way off cannot be entered. Older games bounced the walker back and charged the stride." },
   { rev: 15, note: "BIG MAN at a fork: a pushed wizard leaves by any open side but the way the giant came — the only one if there is one, otherwise the side they choose, the giant's stride hanging until they do (FAQ: at an intersection the other player decides). Older games shove straight ahead whenever that way is open; rounding a corner was never possible before and is allowed in every game." },
+  { rev: 16, note: "BUTT-HEAD's charge is measured as far as the goat's legs reach. Older games searched only six steps of corridor and refused a longer ram as unreachable, even with the legs to make it." },
 ];
 
 export interface GameConfig {
@@ -2361,7 +2362,11 @@ const CARD_EFFECTS: Record<string, AttackEffect | NeutralEffect | CounterEffect>
       if ((state.config.deckRev ?? 1) < 10 || !target) return null;
       const caster = activePlayer(state);
       const legs = state.turn.movementAllowance - state.turn.movementUsed;
-      const d = walkingDistance(state, caster.position, target.position);
+      // Rev 16: the charge is measured as far as the legs reach. Before it,
+      // the search stopped at six steps and called anything past that
+      // unreachable — a goat with eight legs refused a seven-step ram.
+      const reach = (state.config.deckRev ?? 1) >= 16 ? legs : 6;
+      const d = walkingDistance(state, caster.position, target.position, reach);
       if (d > legs) return "the goat charges on legs, not wings — you cannot walk that far this turn";
       return null;
     },
@@ -2369,7 +2374,8 @@ const CARD_EFFECTS: Record<string, AttackEffect | NeutralEffect | CounterEffect>
       if (ctx.fullyStopped || !ctx.defender.alive || !ctx.attacker.alive) return;
       if ((ctx.state.config.deckRev ?? 1) >= 10) {
         const legs = ctx.state.turn.movementAllowance - ctx.state.turn.movementUsed;
-        const d = walkingDistance(ctx.state, ctx.attacker.position, ctx.defender.position);
+        const reach = (ctx.state.config.deckRev ?? 1) >= 16 ? legs : 6;
+        const d = walkingDistance(ctx.state, ctx.attacker.position, ctx.defender.position, reach);
         if (d === 0) return;
         if (d > legs) {
           // The target slipped beyond the charge (a counter-teleport, say):
@@ -3677,7 +3683,9 @@ function attachSustained(
 }
 
 /** BFS steps between cells respecting walls (MENTAL FORCE's 3 moved spaces). */
-function walkingDistance(state: GameState, from: Cell, to: Cell): number {
+/** Steps along real corridors from one cell to another, searched out to
+ * `limit` steps; beyond that the answer is Infinity. */
+export function walkingDistance(state: GameState, from: Cell, to: Cell, limit = 6): number {
   if (cellKey(from) === cellKey(to)) return 0;
   const view = boardView(state);
   const seen = new Map<string, number>([[cellKey(from), 0]]);
@@ -3685,7 +3693,7 @@ function walkingDistance(state: GameState, from: Cell, to: Cell): number {
   while (queue.length > 0) {
     const cur = queue.shift()!;
     const d = seen.get(cellKey(cur))!;
-    if (d >= 6) break;
+    if (d >= limit) break;
     for (const side of SIDES) {
       const step = stepTarget(view, cur, side);
       if (step.kind === "blocked") continue;
diff --git a/packages/engine/test/expansion-combat.test.ts b/packages/engine/test/expansion-combat.test.ts
index 5a13fd1..0468730 100644
--- a/packages/engine/test/expansion-combat.test.ts
+++ b/packages/engine/test/expansion-combat.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
-import { applyCommand, activePlayer, boardView, createGame, gameLos, sustainedOn } from "../src/game";
-import { cellKey, edgeKey, stepTarget } from "../src/board";
+import { applyCommand, activePlayer, boardView, createGame, gameLos, sustainedOn, walkingDistance, type GameState } from "../src/game";
+import { cellKey, edgeKey, stepTarget, type Cell } from "../src/board";
 import type { CardInstance } from "../src/cards";
 import { newExpansionGame as newGame, must, drain, giveCard, toRound2, faceOff, castAt } from "./helpers";
 
@@ -812,3 +812,34 @@ describe("the goat charges on legs, not wings (rev 10)", () => {
     expect(rams).toBeGreaterThan(0);
   });
 });
+
+describe("butt-head's charge reaches as far as its legs (K4T3)", () => {
+  /** Two empty cells seven or eight corridor steps apart on the seed-42 board. */
+  function longRun(state: GameState): { from: Cell; to: Cell; steps: number } {
+    const view = boardView(state);
+    const cells = Object.keys(view.cells).map((k) => { const [x, y] = k.split(",").map(Number) as [number, number]; return { x, y }; })
+      .filter((c) => !state.squareContents[cellKey(c)] && !view.homes.some((h) => cellKey(h) === cellKey(c)));
+    for (const from of cells) for (const to of cells) {
+      const d = walkingDistance(state, from, to, 12);
+      if (d === 7 || d === 8) return { from, to, steps: d };
+    }
+    throw new Error("no seven-step corridor on this board");
+  }
+  for (const [deckRev, ok] of [[16, true], [15, false]] as const) {
+    it(`a goat with eight legs and a target seven or eight corridor steps off: rev ${deckRev} ${ok ? "charges" : "refuses"}`, () => {
+      let { state } = createGame({ playerIds: ["goat", "mark"], seed: 42, sets: ["basic", "expansion1"], deckRev });
+      state = toRound2(state);
+      const goat = activePlayer(state);
+      const mark = state.players.find((p) => p.id !== goat.id)!;
+      const run = longRun(state);
+      goat.position = { ...run.from };
+      mark.position = { ...run.to };
+      state.turn.movementAllowance = 8;
+      state.turn.movementUsed = 0;
+      const card = giveCard(state, goat.id, "butt-head");
+      const r = applyCommand(state, goat.id, { type: "cast", instanceId: card.instanceId, target: { kind: "player", playerId: mark.id } });
+      expect(r.ok).toBe(ok);
+      if (!r.ok) expect(r.error).toMatch(/legs, not wings/);
+    });
+  }
+});