Colossal Rattlewurm is a rare Creature — Wurm card from Outlaws of Thunder Junction Promos (POTJ), collector number 159s. Current market price: — (foil $0.35), TCGplayer market prices via Scryfall.
Colossal Rattlewurm has flash as long as you control a Desert. Trample {1}{G}, Exile this card from your graveyard: Search your library for a Desert card, put it onto the battlefield tapped, then shuffle.