This is the hardest boss in the game at the moment, and i am glad it is. The fight is going to take some teamwork to bring down. We've been working on him as well. I hope the boss stays the way it is for a little bit so someone can defeat it legit. The boss is not impossible. Future bosses should be like this with more…
http://i.imgur.com/oNAEBT4.jpg and http://imgur.com/3FJZHxh (Feat Calculator misses 1 point, put it in tempest magic) are the builds i'd recommend. Encounters: Slot [Chill Strike] as mastery. [Ray of Enfeeblement], [Conduit of Ice], and (Personal preference) [Steal Time] or [Sudden Storm] I prefer steal time for the stun…
Esc / Options / Gameplayed / General / Location Targeting Activation / On release Sudden Storm is also bugged and does 99% reduced damage to mobs being sucked in by singularity. Unless it was fixed this patch.