Savage Ventmaw is a uncommon Creature — Dragon card from Dragons of Tarkir (DTK), collector number 231. Current market price: $0.51 (foil $17.00), TCGplayer market prices via Scryfall.
Flying Whenever this creature attacks, add {R}{R}{R}{G}{G}{G}. Until end of turn, you don't lose this mana as steps and phases end.