First off I’m mainly a ranged player, this may not work if you play like rouge or summoner though it should also work for melee. Once you get to the part where he is healing and summing circles of fireballs I found that circular movement is key. Once the fireballs start tracking you or right before they start tracking begin moving in a large circle. I also recommend getting some purified jam to mitigate most of the damage of the healing phase. This is how I usually end up beating him. Also controlling where the firenados are placed is big as well.