This is The Evil One at its most powerful form, which this melody shows at its finest. It's also used in her new final form during her battle against Airy in the final dungeon on the Golden Ending route. It has a very definitive Final Boss air, considering that Airy is the final boss in the Normal Ending route, and the song is used for her second form.
They have dropped all pretenses and decided to show how much they really mean business. Evil War, the second battle theme, used both against the first form on the Normal Ending route in the final dungeon and against the second form in the Golden Ending route when confronting Airy in the airship.An evil tune that shows the real colors of Airy, being an ugly fairy-like monster, and what a nasty piece of work she really is.