M'Baku, Jabari Chieftain is a rare Legendary Creature — Human Noble Warrior card from Marvel Super Heroes Commander (MSC), collector number 67. Current market price: $0.22, TCGplayer market prices via Scryfall.
At the beginning of your end step, if there is no monarch, target opponent becomes the monarch. Whenever a creature attacks one of your opponents, if that player is the monarch, that creature gets +1/+1 and gains trample until end of turn.