Geralf, the Fleshwright is a mythic Legendary Creature — Human Warlock card from Outlaws of Thunder Junction (OTJ), collector number 50. Current market price: $1.10 (foil $1.38), TCGplayer market prices via Scryfall.
Whenever you cast a spell during your turn other than your first spell that turn, create a 2/2 blue and black Zombie Rogue creature token. Whenever a Zombie you control enters, put a +1/+1 counter on it for each other Zombie that entered the battlefield under your control this turn.