diff --git a/packages/engine/src/game.ts b/packages/engine/src/game.ts
index 843fb0f..b152b94 100644
--- a/packages/engine/src/game.ts
+++ b/packages/engine/src/game.ts
@@ -2062,6 +2062,29 @@ const CARD_EFFECTS: Record<string, AttackEffect | NeutralEffect | CounterEffect>
     kind: "neutral",
     resolve: () => "played out of turn — use it during another player's turn",
   },
+  "swap-home-bases": {
+    kind: "neutral",
+    // "Swap your home base with any other player, as long as you both have an
+    // equal number of treasures on your home bases. You must be within L.O.S."
+    resolve: (state, events, caster, cmd) => {
+      if (!cmd.target || cmd.target.kind !== "player") return "choose whose home to take";
+      const other = state.players.find((p) => p.id === (cmd.target as { playerId: PlayerId }).playerId);
+      if (!other || !other.alive) return "no such living player";
+      if (other.id === caster.id) return "that is already your home";
+      if (!gameLos(state, caster.position, other.position)) return "no line of sight to them";
+      const onHome = (home: Cell) =>
+        state.treasures.filter((t) => t.position && cellKey(t.position) === cellKey(home)).length;
+      if (onHome(caster.home) !== onHome(other.home)) {
+        return "your home bases must hold an equal number of treasures";
+      }
+      const mine = caster.home;
+      caster.home = other.home;
+      other.home = mine;
+      events.push({ type: "positionsSwapped", a: caster.id, b: other.id, aTo: caster.home, bTo: other.home });
+      checkVictory(state, events);
+      return null;
+    },
+  },
   "reuse-spell": {
     kind: "neutral",
     // "You may retrieve any spell you use immediately after you use it (but
diff --git a/packages/engine/test/expansion-combat.test.ts b/packages/engine/test/expansion-combat.test.ts
index f75f7d4..6665a41 100644
--- a/packages/engine/test/expansion-combat.test.ts
+++ b/packages/engine/test/expansion-combat.test.ts
@@ -209,3 +209,20 @@ describe("expansion combat cards", () => {
     }
   });
 });
+
+describe("swap home bases", () => {
+  it("trades homes when both bases hold equal treasures", () => {
+    let { state } = newGame();
+    const me = activePlayer(state);
+    const other = state.players.find((p) => p.id !== me.id)!;
+    other.position = { ...me.position }; // LOS guaranteed
+    const myHome = { ...me.home };
+    const theirHome = { ...other.home };
+    const shb = giveCard(state, me.id, "swap-home-bases");
+    state = must(state, me.id, {
+      type: "cast", instanceId: shb.instanceId, target: { kind: "player", playerId: other.id },
+    });
+    expect(cellKey(state.players.find((p) => p.id === me.id)!.home)).toBe(cellKey(theirHome));
+    expect(cellKey(state.players.find((p) => p.id === other.id)!.home)).toBe(cellKey(myHome));
+  });
+});