To help the aspiring magician A-Bomb get a lesson in hard work, Hulk puts him under the tutelage of the Sorcerer Supreme, Doctor Strange. But when the dreaded Dormammu abducts his teacher, A-Bomb has to use what he learned to save Earth.
Skaar accidentally triggers Ragnarok and incites the ire of Asgard. Detained by the all-seeing, all-knowing guardian of the Bifrost, Heimdall, the Hulks must save Skaar and battle Thor. Soon the Heroes find they must put aside their differences to fight against Malekith and save the realm.