Hellfire Incarnate

Fire Magic: Hellfire Incarnate (炎魔法『業火の化身』) is a Fire Magic spell.

Description
With an open grimoire, the user assimilates a large amount of Fire Magic into their body, which begins to glow and takes on a fire-like appearance, almost as if it has become Fire Magic itself. The user's strength is greatly enhanced, enabling them to punch aside the limbs of a giant demon and to knock it onto its back.