Hellkite Charger is a rare Creature — Dragon card from Modern Masters 2015 (MM2), collector number 118. Current market price: $4.53 (foil $4.30), TCGplayer market prices via Scryfall.
Flying, haste Whenever this creature attacks, you may pay {5}{R}{R}. If you do, untap all attacking creatures and after this phase, there is an additional combat phase.