Kuurth is an ancient, serpentine Asgardian God who has served under The Midgard Serpent for countless ages. When Odin defeated The Serpent, he erased all knowledge of The Worthy's existence until one of his fellow Worthy, Skadi, was brought back to the waking world by Sin, daughter of The Red Skull. After freeing The Serpent, Kuurth and his allies were summoned to Earth in the form of mystical Hammers not unlike Thor's Mjolnir.
When Kuurth descended upon the Earth, he crashed into The Raft and was found by The Juggernaut, who allowed him to enter his body and take control. It was revealed that Cain Marko let Kuurth posses him on purpose. It was also stated that with Cyttorak's power in him, Marko could easily overthrow the influence of Kuurth, but he chose not to.
While in Salem, Missouri, Kuurth encountered Speedball and briefly fought him but was thrown out of the town by Speedball's kinetic powers. Before leaving, however, he split the town in two using his Hammer, Stonebreaker. He later arrived on the outskirts of Chicago where he faced off against The Thunderbolts, who entered The Juggernaut's body and came into contact with Kuurth himself.
After his fight with The Thunderbolts, Kuurth moved on to Las Vegas where he easily overpowered The Heavy Hitters, Nevada's former Fifty-State Initiative team. Hardball, the team's leader, sacrificed his life to stop Kuurth but only ended up throwing him into the desert where he shook off all of the debris he had been buried under and moved on. Kuurth later arrived sixty miles outside of San Francisco where he destroyed a lone gas station and turned its sole attendant into one of The Serpent's followers.
He and the unnamed attendant arrived in San Francisco the next day and began wreaking havoc downtown, The X-Men responded to his assault and confronted him directly.
Repeated attacks by the X-Team failed to stop Kuurth in his tracks, as the rampaging Worthy proved immune to the powers of Magneto, Rogue and Psylocke, among others. Finally, Hope Summers was deployed to mimic the powers of all the mutants present at the scene in an attempt to remove Marko's telepathy-proof helmet. The plan worked, but Kuurth proved to be immune to telepathy even without the helmet.
As a last resort, Magik, Colossus and Kitty Pryde teleported to the Crimson Cosmos, where they met the entity Cyttorak, who powered Marko. They told him that Juggernaut now worshipped another god, The Serpent. The enraged Cyttorak declared Marko to be apostate and withdrew the powers he had granted Marko. Colossus offered himself up as a replacement avatar in order to stop Kuurth's path of destruction.
Marko was stripped of his Cyttorak powers immediately, which were then granted to Colossus, who had become the new Juggernaut. Piotr emerged from the Crimson Cosmos and attacked Kuurth, to the shock and amazement of Cyclops and the X-Men. However, he quickly found that he was consumed by a thirst for destruction, and could not stop himself from destroying the surrounding area. Meanwhile, the runes Kuurth had left on the ground were receding back to him, threatening to reach a deadly critical mass when they reached him. With little time to spare, Colossus attacked Kuurth relentlessly, until finally the Serpent recalled his servant to his side rather than risk his loss.
In the final battle against the Serpent, Kuurth was defeated by the Odin-empowered Wolverine.