Grakmaw, Skyclave Ravager is a rare Legendary Creature — Hydra Horror card from Zendikar Rising Promos (PZNR), collector number 223p. Current market price: $0.43 (foil $0.54), TCGplayer market prices via Scryfall.
Grakmaw enters with three +1/+1 counters on it. Whenever another creature you control dies, if it had a +1/+1 counter on it, put a +1/+1 counter on Grakmaw. When Grakmaw dies, create an X/X black and green Hydra creature token, where X is the number of +1/+1 counters on Grakmaw.