Throat Slitter is a uncommon Creature — Rat Ninja card from The List (PLST), collector number BOK-88. Current market price: $2.39, TCGplayer market prices via Scryfall.
Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever this creature deals combat damage to a player, destroy target nonblack creature that player controls.