Well what I would recommend is that you make one character a White Mage (either as a sub or main class) and you NEED high healing against him as well as "Dispel" It'll help you counter his one ability that gives him Regen. Also his "Dark Breath" (I think that's it) is annoying because once his loses at least 9000 HP it becomes instant 9999 damage. Mainly you need to heal often, revive often, and