9x50 - Fairy Tail

In a flashback to Acnologia's past, the human Acnologia becomes resentful towards dragons and learns Dragon Slayer magic to avenge his hometown; having forgotten his original name, he renames himself after his home's former guardian as a symbol of his hatred, eventually transforming himself into a dragon. In the present, Gray and Lyon create a new ship made of ice, while Erza forces Acnologia's body onto it with her weaponry. Lucy uses all of Fairy Tail's magic to cast Fairy Sphere on Acnologia while he is afflicted, but their power is insufficient. As Acnologia begins to break free, Meldy arrives after contacting other wizards across Ishgar and uses her Maguilty Sense to reinforce the guild's magic with theirs, which successfully immobilizes Acnologia. Meanwhile, Acnologia's spirit defeats all of the Dragon Slayers except for Natsu, whom Wendy enchants with all of their magic in a final effort to overpower Acnologia.