Gau, Feral Youth is a rare Legendary Creature — Human Berserker card from Final Fantasy Commander (FIC), collector number 55. Current market price: $0.21, TCGplayer market prices via Scryfall.
Rage — Whenever Gau attacks, put a +1/+1 counter on it. At the beginning of each end step, if a card left your graveyard this turn, Gau deals damage equal to its power to each opponent.