Stormbreath Dragon is a mythic Creature — Dragon card from Tarkir: Dragonstorm Commander (TDC), collector number 237. Current market price: $0.33, TCGplayer market prices via Scryfall.
Flying, haste, protection from white {5}{R}{R}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) When this creature becomes monstrous, it deals damage to each opponent equal to the number of cards in that player's hand.