Thrull Parasite is a uncommon Creature — Thrull card from Gatecrash (GTC), collector number 81. Current market price: $0.38 (foil $5.29), TCGplayer market prices via Scryfall.
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.) {T}, Pay 2 life: Remove a counter from target nonland permanent.