@Masaki Haruna God Slayer Secret Art: Revenge of the Fallen
Usage: Xavier can only use it once, doing do will drain him of all his magic and do lots of internal damage due yo the intensity of the magic, making this an almost suicidal move.
Description: Xavier focuses all the magical power he has, including the pool of demonic energy he has yet to truly touch upon, and blasts it skyward, breaking up all the earth around him and turning it into volcanic ash. He then brings down the giant pillar of super heated rocks and gad upon his foe in a swirling cyclone, filing the space inside it with a choking cloud of ash that will burn and suffocate those caught inside. An added effect of this magic is that when it's about to end, Xavier can connect to the foes and act as a conduit for the souls of all the people that person has killed increasing the power of the final act, the cyclone exploding outward in a mass of intense flame and pellets of molten rock. Last idea drawn from the connection between ashes and death through cremation.