Ga’trul has nearly seven hundred thousand health, making him staggeringly durable- and the room is set up to take advantage of it.  The space is immense, and while the stairs on either side do not lead up to anything and Ga’trul does not use them, the ‘demon portals’ scattered around the edges of the room are a fast way to move from one point to another- one that he likes to use as he drops meteors all over the room.

Ga’trul is very fond of area of effect spells, mostly fel meteors that he drops into green-defined circles scattered around the room.  He also has a short-range emanation he sometimes uses to deal damage in close combat, though he mostly tries to avoid melee via the portals.  Thankfully, you can use the portals just as well and easily as he can, allowing you to follow him when he jumps from one spot to another.  This first half of the fight, at least, is a relatively simple, if far-ranging, combat with an elite warlock.

The twist comes in when you get him down to just under half his health.  At that point, you get briefly stunned as he warps to the center of the room- and then his invective about how all not in the Horde should die gets a new layer of vitriol, as he is overwhelmed and transformed by the same black-and-white glowing mass you saw previously both in the Sha and attempting to control Rell.  When he has changed to this form, Ga’trul stops using the Demon Portals, and instead floats in one place, using a huge area of effect and long-range spells to deal out constant shadow damage.  Thankfully, you’re probably tough enough to handle what he dishes out, and with the fight simplified, it’s likely to be much faster during the second half.

When Ga’trul is defeated is when things get interesting.  Rell arrives through the door to the temple interior, exclaiming over what happened to Ga’trul- and he is shortly followed by Taran Zhu.  The Pandaren explains that what happened was the ‘Sha’, a force that thrives on negative emotions and takes over those who indulge deeply in them.  Apparently, it has been some time since Taran Zhu saw the Sha express in such a large and dramatic manner