Carnival Hellsteed is a rare Creature — Nightmare Horse card from Return to Ravnica Promos (PRTR), collector number 147★. Current market price: — (foil $0.41), TCGplayer market prices via Scryfall.
First strike, haste Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)