Hell's Thunder is a rare Creature — Elemental card from Duel Decks: Speed vs. Cunning (DDN), collector number 10. Current market price: $0.39, TCGplayer market prices via Scryfall.
Flying, haste At the beginning of the end step, sacrifice this creature. Unearth {4}{R} ({4}{R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)