Hapatra, the Desert Fang is a uncommon Legendary Creature — Human Cleric card from Reality Fracture (FRA), collector number 271. Current market price: $0.18 (foil $0.28), TCGplayer market prices via Scryfall.
When Hapatra enters, for each opponent, put X -1/-1 counters on up to one target creature that player controls, where X is the greatest mana value among cards in your graveyard.