diff --git a/apps/api/src/combat/combat-engine.service.spec.ts b/apps/api/src/combat/combat-engine.service.spec.ts
index ecb9091..492f72b 100644
--- a/apps/api/src/combat/combat-engine.service.spec.ts
+++ b/apps/api/src/combat/combat-engine.service.spec.ts
@@ -266,4 +266,24 @@ describe('CombatEngineService', () => {
 
     expect(first).toEqual(second);
   });
+
+  it('DEFEND mitigates a resolving Heavy Attack by half', () => {
+    const state = baseState({
+      monster: {
+        currentHp: 45,
+        maxHp: 45,
+        stats: { attack: 5, armor: 0, pendingAction: 'HEAVY_ATTACK' },
+      },
+    });
+
+    const result = engine.resolveAction(state, { action: CombatAction.DEFEND });
+
+    // raw = 5; mitigated = 4.545...; heavy * 1.6 = 7.27; * defend 0.5 = 3.636 -> rounds to 4
+    expect(result.events).toEqual([
+      { source: Combatant.PLAYER, target: Combatant.PLAYER, type: CombatEventType.DEFEND },
+      { source: Combatant.MONSTER, target: Combatant.PLAYER, type: CombatEventType.DAMAGE, amount: 4 },
+    ]);
+    expect(result.state.monster.stats.pendingAction).toBeUndefined();
+    expect(result.state.player.currentHp).toBe(100 - 4);
+  });
 });