For a second-to-last boss of a tier, this fight is relatively tame.
This is mostly a single target fight, with some cleave in the Adds Phase. We recommend using Bloodlust when the boss reaches 10% health remaining, because item acts as a soft enrage.
Before you pull the boss, assign half of the raid to be on the west add for the Adds Phase. Assign the other half to the east add.
The boss automatically pulls when you jump down into his room. Make sure a tank jumps in first.
Pull the boss toward the north wall and face it away from the raid. About every 20 seconds, the boss casts a big frontal cone on the current tank (item). The tanks should taunt swap here, and the tank who got hit with the cone should collect green orbs until his item stacks are gone (item).
The raid should stay spread 5 yards apart from each other at all times, while staying as close to the boss as possible. Purple orbs will occasionally appear on random players that charm everyone within 5 yards (item). Anyone caught in the sphere needs to be knocked out of it. This can be done with just about any displacing ability, as well as simply damaging the player. When a player gets knocked out of the sphere, it triggers significant raid-wide damage (item).
A purple dot debuff will occasionally go out on two random players (item). These players have 12 seconds to get out of the raid before the debuff expires and triggers raid-wide damage that does less damage the further away it is. We recommend marking two separate spots in the room for these debuffs to be taken.
The boss also occasionally casts a big purple wave in a random direction (item). This just needs to be dodged quickly.
Every time the boss has taken 33% of his health, it walks to the middle of the room and starts casting a raid-wide damaging explosion (item). While this is happening, everyone should get out of the middle of the room and head toward their assigned side while maintaining the 5 yard spread. The explosion also creates two Oblivion Spheres.
The boss then immediately starts taking 99% less damage and begins the Adds Phase.
Two big adds spawn that need to be picked up by the tanks immediately. One spawns near the east wall and one near the west wall. The adds should be kept more than 40 yards away from each other to avoid item. They should also be faced away from the raid because they cast the same frontal cone as the boss (item). These adds need to be interrupted occasionally and nuked down.
Each of the assigned halves of the raid should stack behind their respective add just after it spawns. This helps to group up the little caster adds that spawn near players in this phase (item). These adds need to be cleaved down and interrupted.
The boss also repeatedly channels a giant shadow beam in a random direction (item). This just needs to be dodged quickly.
The boss will end this phase after about 60 seconds and resume the Boss Phase. Quickly finish off any adds that are left over and make sure to spread back out.
Don’t stand in front of the boss.
Stay spread out by at least 5 yards. Don’t walk into purple orbs.
If you get a swirly purple debuff, take it out of the raid to one of the designated spots.
Dodge the random shadow wave from the boss.
Stack behind your assigned big add and kill it while cleaving little adds.
Dodge the random giant beam from the boss.
Staying spread at least 5 yards for the Oblivion Spheres is the most important thing to focus on in the boss phase. Stacking on your assigned add for the little add spawns is the most important thing in the add phase. Everything else is pretty generic don’t stand in fire mechanics.
It’s recommended to knock people out of the spheres as soon as possible, but they may need to be staggered a bit depending on the health of the raid. If possible, displacing abilities should be talented into in order to help free people.
The tanks should try to stay at the lowest possible amount of stacks of Annihilation. This means running around a bit when you don’t have aggro on the boss. Be careful not to be near other players too much, because getting mind controlled by a sphere could be really bad.
The big frontal from the boss is magic damage. Consider using your big defensive cooldowns on this frontal, especially if you end up having several stacks of Annihilation.
The major raid damage taken in the boss phase is from breaking people out of the spheres and from the two Imminent Ruin debuffs expiring at the same time. There is no random dot damage, so it’s all really just blanket healing.
The major damage taken in the add phase is from the initial raid-wide blast at the start of the phase, and the random-targeting mind flays from the little adds. Spot healing is a bit more impactful in this phase.