Crater's Claws is a rare Sorcery card from Khans of Tarkir (KTK), collector number 106. Current market price: $0.29 (foil $0.60), TCGplayer market prices via Scryfall.
Crater's Claws deals X damage to any target. Ferocious — Crater's Claws deals X plus 2 damage instead if you control a creature with power 4 or greater.