He will walk slowly around the battlefield, then leap and attack when he is close.
Don't try to avoid him (unless you need time to heal or cast Aero on yourself). Just try to dodge his sword and get close. If he misses too many times in a row, or if you do not hit him with a full combo, he might say something, then summon a large explosion around him. If you are trapped in it, you will get hit twice. If you are not surrounded by Aero, or cast Cure very quickly, there is a good chance you will die as this attack is fast and powerful. When you are within striking distance, hit him as many times as you can (one combo will do; more than that, and he will counterattack).