Hapatra, Vizier of Poisons is a rare Legendary Creature — Human Cleric card from Lorwyn Eclipsed Commander (ECC), collector number 123. Current market price: $0.26, TCGplayer market prices via Scryfall.
Whenever Hapatra deals combat damage to a player, you may put a -1/-1 counter on target creature. Whenever you put one or more -1/-1 counters on a creature, create a 1/1 green Snake creature token with deathtouch.