Kuro, Pitlord is a rare Legendary Creature — Demon Spirit card from Champions of Kamigawa (CHK), collector number 123. Current market price: $0.45 (foil $7.25), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, sacrifice Kuro unless you pay {B}{B}{B}{B}. Pay 1 life: Target creature gets -1/-1 until end of turn.