This fight has a LOT of moving parts. It’s the first real add-management fight of this tier.
Phase One has a bit of stacked AOE, but Phase Two is entirely single target. We recommend using Bloodlust in Phase Two, because the tanks and raid take crazy high damage and you start to run out of room on the platform.
The general kill priority for the adds in the fight is: Ichor > Bloodhexer > Crawgs > Crusher.
On pull, you will be able to AOE nuke all the existing adds down pretty quickly. Just keep the Crusher faced away from the raid, constantly interrupt the Bloodhexer, and AOE stun the Crawgs.
A small purple circle will appear on the ground occasionally throughout the fight (item). One ranged dps or healer needs to stand in it until it disappears. This player will take significant magic damage for 20 seconds.
A red swirly debuff will go out on two random players occasionally throughout the fight (item). These players need to get away from the raid separately until the debuff expires and does raid-wide damage. When the debuff expires, it will spawn 3 small adds near each player that need to be dispelled quickly, which instantly kills them. Mass Dispel and Arcane Torrent are great tools for this.
A wave of Crawgs will frequently spawn near the edge of the platform. They heal for any damage they do, and they explode for raid-wide damage if they reach full energy. Simply group them up on the boss, stun them, and kill them.
Two Bloodhexers will occasionally spawn near the edge of the platform. DO NOT let these Bloodhexers near each other (item). One of them needs to be hard cc’ed, while the other one is immediately interrupted, brought to the boss, and killed quickly. Then you should break the cc on the other Bloodhexer, quickly kill the Ichor it creates, and kill that Bloodhexer quickly as well. The Ichor will try to get to Zul, and will heal him if it does (item).
A Crusher will spawn near the edge of the platform shortly after every set of Bloodhexers. A tank needs to bring this add near the boss and face it away from any players because it has a frontal cleave (item). A few seconds before the Crusher gets to full energy, that tank needs to take it at least 30 yards away from any other enemies. The Crusher will then cast a damage buff for its allies within 30 yards (item), and then the tank should bring it back near the boss.
At 40% health remaining, Zul will cast a raid-wide knockback and begin Phase Two (item).
Finish off any adds that are leftover from Phase One. No more adds spawn once in Phase Two.
Keep Zul exactly in the center of the platform and immediately face him away from any other raiders. He will frequently cast a frontal cone on the current tank (item). This will put a 20 second bleed on the tank that stacks and refreshes with more applications. At 3 stacks, the tanks should taunt swap, and the tank with stacks should get to the absolute edge of the platform a few seconds before the bleed expires. When the bleed expires, it creates a massive red pool that the raid should avoid standing in.
Two random players will occasionally be feared and start running toward the closest edge of the platform (item). Both players should be dispelled once they are at least 30 yards away from the raid, but before they get to the edge of the platform. Dispelling these players does a huge amount of raid-wide damage and spawns 5 of the small adds that also need to be dispelled. Again, Mass Dispel and Arcane Torrent are great tools for these adds.
The small purple circles that need to be soaked continue to spawn during this phase as well (item). They are dealt with the exact same way as in Phase One, but now there can be two at a time and they could be in the red pool from the tank debuff.
Ranged dps stand in little purple circles if no one else is in it.
Focus on killing adds in this priority: Ichor > Bloodhexer > Crawgs > Crusher.
Don’t stand in front of the Crusher. Don’t follow it when it runs away.
If you get a swirly red debuff, get it out of the raid to one of the designated spots.
Don’t stand in front of the boss. Don’t stand in any red pools.
Avoid little adds.
Always follow the kill priority: Ichor > Bloodhexer > Crawgs > Crusher.
Dispelling the little adds is incredibly important in this fight. Mass Dispels from priests and Arcane Torrents from blood elves really help to trivialize this mechanic. Otherwise, single dispels from healers or dps will need to be organized.
The boss isn’t actually tanked in the first phase, so one tank will handle the Crusher while the other handles the Crawgs and Bloodhexers.
The tank with the Crusher should have a defensive ready for the cleave it does regularly.
In the second phase, the current tank needs to make absolutely sure to face the boss away from everyone. The frontal he does every few seconds applies a heavy physical dot, so the current tank should be the only one getting hit. The taunt swap needs to happen at 3 stacks of the dot, and the tank with the dot needs to let it expire really far away from the raid, preferably on the absolute edge of the platform.
Most of the raid damage taken in the first phase is from the random-target cast the boss does constantly, as well as the big raid-wide nuke from Dark Revelations. Make sure everyone is topped up before and after the Revelations.
In the second phase, everyone in the raid will have a relatively light dot debuff. The big raid damage will come from dispelling the two players with Deathwish. The tanks will also have a heavy dot on them as they taunt swap.
The player soaking the Pool of Darkness will need big heals for 20 seconds.
Be ready to dispel the little adds that spawn from Dark Revelation in the first phase, and Deathwish in the second phase.