As an Assassin tank on this fight I find it much easier to just have everyone behind the boss and mostly in melee range (or close to the previous GTAOE). For 100% easy mode equip 2-piece pvp (dps) set bonus.
With that 2pc bonus, you can safely interrupt every single incinerate yourself while kiting him around the room.
I generally start by pulling him to the console (that starts the encounter) corner, and going clockwise from there. ~3 AOE's per doorway side, and 1-2 in the center where adds spawn.