The Art of War
Ultimate Spell — Buff • Cost: 3
Your Peace Hero is unstoppable, has swift strike, and gets +2 ATK/+2 armor until your next upkeep.
Blue • Peace Ultimate Magic
Swift Strike Rulings
Combat damage is dealt simultaneously if the attacker and the thing it's attacking both have swift strike. — SirlinIf swift strike damage kills a unit or hero in combat that does not have swift strike, the non-swift strike unit or hero dies before it gets a chance to deal combat damage. — Sirlin
Having a detector (or a Tower add-on) doesn't help against the unstoppable keywords. Even then, unstoppable attackers can ignore patrollers. — Sirlin