Oberon in his Third Ascension form from Fate/Grand Order. His hair is black, and he wears a blue diamond hairband. He wears a white shirt, black pants, and a large black fur-trimmed cloak comprised of multiple torn fairy wings. His right hand remains humanoid, but his left arm turns into a dark claw, and his legs and feet also turn dark. He gains a pair of dragonfly wings, which aren't capable of helping him fly.
Major spoilers for Lostbelt no. 6: Fairy Realm of the Round Table, Avalon le Fay!
This is his true Pretender-class form when he awakens as Oberon Vortigern, the Insect of the Abyss summoned to destroy the British Lostbelt.
This Ascension is considered a major spoiler for the events of Lostbelt no. 6: Fairy Realm of the Round Table, Avalon le Fay. The spoilers tag MUST be added when tagging this Ascension!
This tag implicates oberon_(fate) (learn more).