Roar of Challenge is a uncommon Sorcery card from Khans of Tarkir (KTK), collector number 145. Current market price: $0.24 (foil $2.27), TCGplayer market prices via Scryfall.
All creatures able to block target creature this turn do so. Ferocious — That creature gains indestructible until end of turn if you control a creature with power 4 or greater.