Appearing in Ragnarok (story)
Objects and vehicles
A viking called Ragnarok marvels over his magic stone and boasts about the power it will give him. Suddenly, there is a loud noise, and a crewman rushes in to tell his captain that they hit an iceberg. Ragnarok is thrown from the boat and his magic stone is broken in half, and he submerges with only one half in his hand.
Meanwhile, the Tortugas Ninja and Moycat are on their way back from the Sharkius Branchii ordeal, when they take a stop in Yucatán for a much-needed break. After playing on the beach for a bit, the team dozes off, only to wake up in the midst of a flood. They pile on Moycat's car for safety, and use his radio to call Splinter, who is also experiencing a flood back home. He points the radio receiver to the TV, where Abril is reporting that the flooding is happening worldwide due to abrupt melting in the North Pole.
Naturally, the Tortugas and Moycat head to investigate, somehow stopping to grab some snazzy snowsuits along the way. When they arrive, they come across a cave where a slavedriver is whipping a mutant walrus. Moycat takes out the slaver and the walrus tells them his name is Ruk, and that he and a bunch of other walruses were mutated by the half of Ragnarok's stone that he has held onto, and forced to melt the icecaps in an effort to find the other half of the stone. To make matters worse, Ragnarok had been killing the walruses that had angered of failed him, with Ruk one of the last, if not the last, remaining.
Moycat and the Tortugas exit the other side of the cave to find Ragnarok, and attempt to attack him, but he knocks them silly with this stone half. Ruk reveals that he has found the other stone half, but Ragnarok blasts him before he has a chance to use it. Ruk's half of the stone goes flying, and Moycat recovers it, but Ragnarok threatens him with his sword. Leonardo defends Moycat with his katana, and the two engage in a swordfight which ultimately finds Leo victorious, but he takes a cheap swipe at a nearby Rafael from the ground, surprising him and then recovering long enough to snatch the other half of the stone from Moycat.
Using the stone at its whole once more, Ragnarok grows to massive proportions, and plows through the Tortugas and Moycat with no effort. Fortunately, aid comes from an unsuspected source - the Norse god, Balder, who takes task with Ragnarok's actions and freezes him solid. The Tortugas ask Balder to heal Ruk, which he does, but Ruk also asks to stay a mutant so that he can protect the other walruses and prevent something like this from ever happening again. Balder agrees, saying that there is a lot threatening the seals and walruses of the world.
After watching the glaciers reform, the Tortugas and Moycat bid farewell to their new friend in the north, and decide to stop for pizza on the way back.