You are most likely timing the aoe wrong if you get "one-shot" after he reappears. The right moment to do some aoe is when he vanishes the 2nd time. So, after he vanishes 1st time, we usually just stack up -> he reappears and does his thing -> vanishes for the 2nd time -> at this point everybody that can throw some aoe should do so and he will almost instantly reappear due to taking dmg from the aoe We've found out that stacking up is very beneficial since it helps the healer and all but guarentees that your aoe spells will hit the boss.

My group killed it yesterday aswell. I was totally convinced after first wipe that it is NOT doable due to the "bug" but others insisted on trying some of the strategies and tactics found on these sites. So we did and it died on like a 4th try or something. My tank gear was mediocore at best (juggernaut) and had like 17,2k ish hp with BH buff. He does Force Storm (or something like that) at 44-45% ish, which you just need to run away from, then at 33-35% ish he does the uber Force Lightning channel that "one-shots" you, unless you pop every defensive cooldown you have. Endure Pain, Invincible, Trinket etc and for me it was easily survivable IF the channel was interrupted before it ticks for the 2nd time, which is easily achieved. After that its just a dps burn avoiding the rock boulders crashing down on you. At low health he goes in the immunity bubble in which he is supose to die but we had this bug once too and he stayed in combat and stompped our group while we could do nothing to him since he was immune to everything. But all in all very doable boss once you get down the moment where you need to use all cd's and be quick on the interrupt.