Ravenous Squirrel is a uncommon Creature — Squirrel card from Modern Horizons 2 (MH2), collector number 375. Current market price: $0.25 (foil $0.33), TCGplayer market prices via Scryfall.
Whenever you sacrifice an artifact or creature, put a +1/+1 counter on this creature. {1}{B}{G}, Sacrifice an artifact or creature: You gain 1 life and draw a card.