Ahn-Crop Champion is a uncommon Creature — Human Warrior card from Amonkhet (AKH), collector number 194. Current market price: $0.20 (foil $1.20), TCGplayer market prices via Scryfall.
You may exert this creature as it attacks. When you do, untap all other creatures you control. (An exerted creature won't untap during your next untap step.)