Pugnacious Hammerskull is a rare Creature — Dinosaur card from The Lost Caverns of Ixalan Promos (PLCI), collector number 208s. Current market price: — (foil $0.96), TCGplayer market prices via Scryfall.
Whenever this creature attacks while you don't control another Dinosaur, put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)