Fairy Tail: Final Series

Synopsis

Gray almost succeeds in freezing Zeref and sacrificing himself with Lost Iced Shell, but Natsu stops Gray and reconciles with him, promising to defeat Zeref without dying. As they battle, Zeref reasons that Natsu is incapable of killing him without Fire Dragon King Mode. The two briefly halt their duel upon sensing the arrival of Acnologia, who finds Irene's corpse and cruelly mutilates it in front of Erza and Wendy, recognizing her as his "mother" for creating his powers. Meanwhile, Cana casts Fairy Glitter on August, but he is unfazed by the attack. Intrigued by Gildarts and Cana's familial relationship, August enrages Gildarts by threatening Cana.

(Source: Wikipedia)