Dragon Tempest is a rare Enchantment card from Dragons of Tarkir (DTK), collector number 136. Current market price: $2.89 (foil $19.73), TCGplayer market prices via Scryfall.
Whenever a creature you control with flying enters, it gains haste until end of turn. Whenever a Dragon you control enters, it deals X damage to any target, where X is the number of Dragons you control.