This mutt has been available on the PTR for some time. He had way too much health on 10 man during my initial times with him. He’s much more manageable now. You’ll find that this fight is a slight DPS check and skill check.
When you first engage the encounter, the tanks will need to pull him back to a corner and point him away from the raid. The rest of the group will need to stand and spread out around him. Naturally, there is a tank switch involved. When your first tank eats the shadow debuff, your second tank needs to taunt right away until that debuff wears off. The second tank needs to stay off near the side so as to not get hit by Searing Shadows.
Watch out for large, glowing circles around the room. Stay out of those. The DPS check kicks in when he does his Gaze of Occu’thar ability. He launches those little eyeballs of his from the top of his head and sends them towards every player. They’ll hit for around 5000+ damage a second. Have everyone gather up in one central location and light up your AoE. If you don’t kill the eyes quick enough, they’ll explode and dish out 25000 damage to everyone nearby. Spread back out as soon as that’s done!
Enjoy the ridiculous amount of PvP gear that’s bound to drop!
Here’s a kill video from Memento Mori and Method on 25 man in the PTR