Warhorn Blast is a common Instant card from Kaldheim (KHM), collector number 38. Current market price: $0.21 (foil $0.12), TCGplayer market prices via Scryfall.
Creatures you control get +2/+1 until end of turn. Foretell {2}{W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)