Flame Wings

'Overwhelming might?' Arthur sneered at that moment, clasping his hands together. If the Gruelling Devil wished to compete in terms of magic, the crimson-eyed man was happy to comply.

Watching the black and white lightning crackle with an apathetic expression, Arthur tapped his chest. 

Whoosh! Whoosh!

Two wings forged using flames sprouted at his back, spilling voracious fire. Arthur felt a rejuvenating sensation course across his physical body. To forge wings on one's back was not an easy task, and required an enormous amount of mana.

Arthur was only able to maintain it due to the existence of the Mana Stone that continued to pump mana at a terrifying pace into his mana circuits. 

As long as the wings burnt, Arthur's mana would be drained at a terrifying pace.

But the wings were also incredibly useful.