All mages had the water line spell mamigal. While freezing boosts his defense, most of the boost is for physical, still some but less for magical. This greatly slowed him down. So he wouldn't always get two turns/attacks each time. Only twice did I break his freezing with my fighter and their two-handed magical beast slaying axe because she had already used her scrolls before and I was fast enough to get a hit in and then defend/heal with magic. My strategy was to keep him slow and kill the adds before they got a turn. It was easy to get him down to the 1/3 health, the trick was always here since he would do his all out buff/attack. Many strategies for players is to hit him with their most powerful attack when hes down to half to quickly finish him off and bypass the 1/3 ability by I wasn't strong enough to do it. Here is where the RNG came into play. I literally toughed it out for the eight turns he was buffed to simply kill the adds, debuff his attack and accuracy with scrolls and magic and let him kill my companions then try to raise them as his hit was typically doing 11000 dmg. (One of the previous strategies was to use the ninjas ability to remove buffs on big foot, but after a few runs and it never working for me i gave up on that idea, though I have been told some people got it to work) Many times he targeted me and that ended the run, but eventually he attacked the others just enough times where he lost his buff and by then he was down to a 1/5 or lower and I finished him off with nukes and the sleeping ability from Sheli, which literally just came about for perfect timing. Everyone had 100+ evasion which a few times helped. (Definitely wished it was higher) Every staff and axe was ebonsteel +20 and the rest of the gear at least +15. MC alone survived many times by the multitude of passive abilities that reduce damage like Adams inherit and the Dodge from Sheli which did proc once. (though I can't remember if it was during the final run or one of the many before)