Ok this was the final boss battle in the Warehouse. What you basically need to do to beat it is to take down the minion-boss first. This is because he can rebirth anytime. You can beguile the boss to do this by having him "Fire Nova". With a few of your school's biggest hit spells. Once you get the final boss singled out alone, put a lot of fire shields up and hammer him down with a lot of attacks with blades. That is how I defeated him so if you have your own strategy comment it here for others.