Bark-Knuckle Boxer is a uncommon Creature — Raccoon Berserker card from Bloomburrow (BLB), collector number 164. Current market price: $0.21 (foil $0.27), TCGplayer market prices via Scryfall.
Whenever you expend 4, this creature gains indestructible until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)