Seraphic Steed is a rare Creature — Unicorn Mount card from Outlaws of Thunder Junction Promos (POTJ), collector number 232p. Current market price: $0.38 (foil $0.50), TCGplayer market prices via Scryfall.
First strike, lifelink Whenever this creature attacks while saddled, create a 3/3 white Angel creature token with flying. Saddle 4 (Tap any number of other creatures you control with total power 4 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)