Wolf of Devil's Breach is a mythic Creature — Elemental Wolf card from Shadows over Innistrad (SOI), collector number 192. Current market price: $0.41 (foil $0.69), TCGplayer market prices via Scryfall.
Whenever this creature attacks, you may pay {1}{R} and discard a card. If you do, this creature deals damage to target creature or planeswalker equal to the discarded card's mana value.