Quetzalcoatl

Well, he looks pretty strong but I used the hit and run tactics and I beat him with the best darn mage known as Miriam. Just use her, use the kamikaze formation and then when you have dealt enough damage and you are about to die, retreat and go at it again after you've healed.

U can have other characters heal them if they know the heal power. Or just use herbs. XD Hope this is helpful.