The Doom Stone - S3.E7

Determined to turn the life-giving rain that nourishes the Multiverse into lethal acid rain, Tenoroc despatches the dim-witted Troll to find the evil Doom Stone, and use it to corrupt the Enchanted Forest's mystical Stone Circle. Virtually unstoppable thanks to his stone skin, Matt, Roxie and Gomez find Troll one of their toughest opponents, and time is running out - for the whole Multiverse.