Switches forms every 10%, blue, green, brown. In blue mode he sometimes charms for 12 seconds (Unyielding Compulsion), so far always the tank. In green mode he dots your group (Blistering Skin). In brown mode he will cast Infernal Blast when hit with any kind of fire spell/proc (about 55k area damage after shielding).
He'll also every now and then start to absorb your attacks, and convert them into an exceptional heal.
Note that he seems to power up if you are slow. Take more than about 10-12 minutes and he starts hitting for 100k.
