<Tr> <Th> 46 </Th> <Td> 6 </Td> <Td> "Gone Gustav Gone" </Td> <Td> Elaine Bogan </Td> <Td> FM De Marco </Td> <Td> June 26, 2015 (2015 - 06 - 26) </Td> </Tr> <Tr> <Td_colspan="6"> Gustav visits the riders on Dragon's Edge saying he is now ready to be trained, as promised by Hiccup, to be a proper dragon rider . After much delaying and' keeping Gustav busy' by the riders, Gustav takes the Dragon Eye to go on a treasure hunt . When the riders find out they make it clear to him that he is too immature to become a rider, Gustav runs from the island in the night . Dagur captures him and Fanghook, whereby Gustav appears to become a part of their crew claiming he knows how to get Dagur the Dragon Eye . A trade takes place, but Gustav decides to stay with Dagur . He later double - crosses Dagur returning the Dragon Eye to Hiccup and saving both of them in the process . Hiccup also discovers a new series of lenses for the' Dragon Eye' . </Td> </Tr> <Tr> <Th> 47 </Th> <Td> 7 </Td> <Td> "Reign of Fireworms" </Td> <Td> T.J. Sullivan </Td> <Td> Art Brown & Douglas Sloan </Td> <Td> June 26, 2015 (2015 - 06 - 26) </Td> </Tr> <Tr> <Td_colspan="6"> It becomes apparent that the twins are the rightful and lawful owners of the island on which the riders have made base . They enforce their royalty rights immediately getting the other riders doing meaningless and annoying tasks . During all this Fireworm dragons start arriving on the island as part of their migration; however being Fireworm dragons they start burning the island down . After the twins throw everyone in the' dungeon' they realise they need the other riders to stop the island becoming a pile of ash . They agree that all the group are equal owners to the island and they in turn agree to help . It is only the Night Terrors forming the shape of the Fireworm Queen that gets the Fireworms to leave the island . </Td> </Tr>

Dragons riders of berk season 3 episode 21