Unstoppable Slasher is a rare Creature — Zombie Assassin card from Duskmourn: House of Horror Promos (PDSK), collector number 119p. Current market price: $5.14 (foil $5.28), TCGplayer market prices via Scryfall.
Deathtouch Whenever this creature deals combat damage to a player, they lose half their life, rounded up. When this creature dies, if it had no counters on it, return it to the battlefield tapped under its owner's control with two stun counters on it.