Hapatra's Mark is a uncommon Instant card from Amonkhet (AKH), collector number 169. Current market price: $0.22 (foil $1.78), TCGplayer market prices via Scryfall.
Target creature you control gains hexproof until end of turn. Remove all -1/-1 counters from it. (A creature with hexproof can't be the target of spells or abilities your opponents control.)