Howl of the Horde is a rare Sorcery card from Khans of Tarkir (KTK), collector number 112. Current market price: $0.26 (foil $0.41), TCGplayer market prices via Scryfall.
When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy. Raid — If you attacked this turn, when you next cast an instant or sorcery spell this turn, copy that spell an additional time. You may choose new targets for the copy.