Rubblebelt Rioters is a uncommon Creature — Human Berserker card from War of the Spark (WAR), collector number 215. Current market price: $0.24 (foil $0.34), TCGplayer market prices via Scryfall.
Haste Whenever this creature attacks, it gets +X/+0 until end of turn, where X is the greatest power among creatures you control.