Return of Thor Bonecrusher is the sixth episode of Dragons: Race to the Edge, Season 5. It was released on August 25, 2017.
When Thor Bonecrusher is needed to rescue hostages taken by the Bandits, Snoutlout tries to help but accidentally brings to life Thor’s evil twin – Anti-Thor – who sides with the Bandits. 
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Outcasts arrive unexpectedly on the shores of the Edge , disguised as women, which annoys Snotlout. They say that they're chief Alvin has been captured by bandits and they need none other than Fishlegs as Thor Bonecrusher to help them rescue him. At passing what the Outcasts said on to Hiccup and the other Riders, Hiccup says it's a bad idea and they should think of another way. But Snotlout invites Fishlegs to his hut to tell him all the marvelous stories of Thor Bonecrusher from last time. Fishlegs agrees to help and asked Snotlout to hypnotize him with a ball and chain. Once under, Snotlout tells him to love Meatlug at Fishleg's request, to snap out of the hypnosis when he claps three times, and misinterprets his other request to be more mindful to being "anti-heroic" instead.
Once on Outcast Island, the plan seems to be working at first until it's discovered that "Thor" is actually working on the bandits' side. Snotlout is locked up with Alvin and the remaining Riders now have to find a way to rescue both. "Thor" then unlocks Snotlout only to hold him as a hostage when a battle breaks out. In the battle, Snotlout finally manages to clap three times to bring Fishlegs out of hypnosis, but it didn't seem to work. The remaining Riders regroup back at the Edge while Snotlout is continued to be held as a hostage. "Thor" sends Meatlug to the Edge with a message, and the Riders soon arrive ready to meet the demands. As it turns out, the clapping did work and it was Fishlegs, not "Thor" that came up with the rescue plan after that, and caught the bandits off guard, showing he's had Thor's warrior spirit in him all along. Alvin and the Outcasts are set peacefully on their way.
Meanwhile, the bandits report to Krogan that the Ice Tail Pike fish they were demanding for ransom for Alvin was a failure, and Krogan's new partner, Viggo, agrees that tougher measures will be taken in the future to be sure they don't fail again.
- Alvin makes his Race to the Edge debut
- Viggo is seen to be officially alive, but with the left side of his face horribly burned.
- Flashbacks are seen from the episode "Big Man on Berk".
- The way the Outcasts disguise themselves as women is similar to how two Roman soldiers disguised themselves as Bog-Burglars in "How to Speak Dragonese".
- This is the first episode that Viggo appears in that Ryker doesn’t.
- Jay Baruchel as Hiccup Horrendous Haddock II
- America Ferrera as Astrid Hofferson
- Christopher Mintz-Plasse as Fishlegs Ingerman
- T.J. Miller as Tuffnut Thorston
- Andree Vermeulen as Ruffnut Thorston
- Zack Pearlman as Snotlout Jorgenson
- Mark Hamill as Alvin the Treacherous
- Alfred Molina as Viggo Grimborn
- JB Blanc as Jarg
- Jeff Bennett as Outcasts
- Hakeem Kae-Kazim as Krogan