Rhet-Crop Spearmaster is a common Creature — Human Warrior card from Amonkhet (AKH), collector number 26. Current market price: $0.04 (foil $0.40), TCGplayer market prices via Scryfall.
You may exert this creature as it attacks. When you do, it gets +1/+0 and gains first strike until end of turn. (An exerted creature won't untap during your next untap step.)