Immerseus is the first boss in the Siege of Orgrimmar raid, and will be available on Normal and Flex difficulties from launch.

The Immerseus encounter is a very simple two-phase fight with few mechanics. The encounter features frequent, moderate raid damage, heavy tank damage, and raid-wide burst AoE at the end of every Phase 2. It is also a healer-gimmick fight in a way; healers must target and heal friendly NPCs during the fight’s second phase, and a failure to execute this properly will both lengthen the fight and endanger the raid.

Immerseus stands in the midst of a large pool of water. Players who come into contact with the water in the central pool will take moderate damage and be knocked back. This will occur throughout the fight. Note that the channels of water radiating out from the central pool are completely safe to stand in; it is just the central pool that behaves this way. Due to the mechanics of the fight, the raid should spread itself out evenly throughout the room, ensuring there are players in all “slices” of the encounter area.

At the start of the encounter, Immerseus will have both full health and a full Corruption bar. Phase 1 will persist until players deplete Immerseus’ health, at which point Immerseus will split into a collection of 25 puddles. Phase 2 requires players to destroy hostile puddles and heal friendly ones, whilst the puddles steadily move towards the pool in the centre of the room. Each puddle that is destroyed or fully healed will remove 1 Corruption from Immerseus’ Corruption bar, while each puddle that is not destroyed or fully healed will explode upon reaching the pool and deal heavy raid damage. Once the puddles have reached the centre of the room, Immerseus will reform and begin Phase 1 again, with a reduced Corruption bar.

The fight ends when Immerseus would reform after Phase 2 with 0 Corruption. With perfect play, this would take 4 cycles, but most groups are likely to require more like 5 or 6 cycles in order to defeat the boss.

So, let’s start with Phase 1, because starting at the beginning makes sense, yes?

Immerseus primarily attacks the tanks during Phase 1, dealing moderate melee damage and attacking the current tank with Corrosive Blast. This is a frontal cone attack that damages anyone in front of the boss for heavy Shadow damage, and leaves a lingering debuff (also called Corrosive Blast) that increases subsequent Corrosive Blast attacks to deal additional damage. This requires frequent tank swaps, and also requires the tanks to position themselves in different “slices” of the room so that they do not inadvertently get hit by their co-tank’s Blast.

If you are assigned to heal the tank, remember that you, too, must avoid being hit by the Corrosive Blast, because it is likely to one-shot you. (This happened to me *covers hand with mouth* mumbledy-mumble times on the PTR. I am not proud of it.) Since the tanks will be taunting it is challenging to keep both tanks in range of you without taking the Corrosive Blast damage yourself. I usually stand with the off-tank while healing the current tank, then swap positions when they swap tanking duty. Corrosive Blast has a cast bar, so you can watch for this and move out of the way if necessary.

Symbiosis will assist 3 of the 4 non-Druid tank specs in mitigating this damage. Don’t bother with it if you have a Warrior tank; magic attacks cannot be dodged.

About once a minute, Immerseus will stop attacking the tanks and begin to cast Swirl. He will face one of the four Cardinal directions and expel a stream of water that will damage, and knock back, any players it hits. Immerseus rotates 135 degrees clockwise while continuing to spray the stream, endangering a wide swath of the room.

Swirl can be outrun with speed boosts, or avoided by ducking counter-clockwise out of the area of effect in the few seconds before the Swirl effect begins. If you are caught in the Swirl, do not run with it (clockwise) or stand still – in either case you will take very heavy damage and may die. Run counter-clockwise and you will only take one, moderately-sized hit of the Swirl damage.

About every 8-10 seconds, so long as Immerseus isn’t using Swirl or Corrosive Blast, he will spawn Sha Splash puddles beneath every player‘s feet. These deal an initial hit of moderate Shadow damage and then will continue to deal damage over time as long as the player stands in it.

This necessitates frequent movement, and in 25-player difficulty, will require players to carefully position themselves so that Sha Splash puddles overlap and do not cover the entire area. This will also cause melee to spread out. Although every player must move each time Sha Splash occurs, it is not wise to attempt to stack up for AoE healing, since the initial damage from the Splash spawn of multiple Splashes will be very dangerous.

During Swirl, a second type of puddle spawns – one with a blue ring, that moves erratically across the ground. Players who contact this puddle will take moderate damage and be knocked into the air. This is especially dangerous if you are in the path of the Swirl, and you will likely die since you will be unable to counteract Swirl damage whilst in the air.

Once Immerseus’ health pool reaches zero, Phase 1 completes and Phase 2 begins. Immerseus sinks into the pool of water at the centre of the room and Splits into 25 small puddles, which fly through the air until they land near the perimeter of the encounter area.

Upon landing, the Puddles will begin to race toward the centre of the room, where they will eventually merge back into Immerseus and deal raid-wide AoE when they do. In order to prevent as much of this AoE as possible, players must destroy or heal the adds. The two colours of Puddle adds indicate whether they are for DPS to deal with (the Sha Puddles, black) or for healers (the Contaminated Puddles, blue).

I’ll note briefly that the Sha Puddles are not really your problem, but you can do a few things to help your raid out. The Puddles are susceptible to slows, stuns, and roots, and giving the DPS more time to reach and kill the Sha Puddles will mean you have less work to do at the end of the Phase!

Mass Entanglement, Typhoon, and Ursol’s Vortex all work against the Sha Puddles.

Leg Sweep (although, you know, these guys don’t have legs…) or Charging Ox Wave will assist your raid in managing the Sha Puddles.

Fist of Justice will allow you to stun a Sha Puddle every Phase. Blinding Light is not worth it due to the cast time.

Void Tendrils are simply amazing here, especially if you are near a Death Knight who can Gorefiend’s Grasp the Puddles together.

Earthbind Totem is great, but Earthgrab Totem is even better! Capacitor Totem can also stun the Sha Puddles.

While Contaminated Puddles are immune to slows and all forms of CC, healing the Puddles gives them a debuff that decreases their movement speed. It is important that you get a heal on each Contaminated Puddle near you ASAP to slow them down and give you more time to finish healing them.

Contaminated Puddles are not added to raid frames, so you will either need to target them directly, make mouseover macros for your spells, or create a targeting macro to auto-target them.

Some spells simply do not work on Contaminated Puddles. I’ve taken this screenshot from my raid’s Immerseus 25N kill. Down at the bottom you’ll see a list of a bunch of spells that were pure overheal and did zero effective healing. These spells actually just don’t work on the Puddles. I mean – in order for them to be 100% overheal, the Puddles would have had to be on full health. But when they’re on full health, they become a different creature type, so there’s only a split-second where a Contaminated Puddle exists at full health. I find it very difficult to believe that all of those spells were only used in that brief split-second; far more likely – and consistent with reports from 25H testing on the PTR – Puddles are ineligible targets for most raid CDs and smart heals.



Wild Mushroom: Bloom will heal the Contaminated Puddles, and Incarnation and Nature’s Vigil are probably your best Talents for this fight. Efflorescence does not heal Puddles, nor does Tranquility or Wild Growth.

Healing Spheres are an excellent way to heal up the Contaminated Puddles quickly. Revival will heal the Puddles, but Uplift, EH, ReM, or your Mastery won’t. Revival should be used on the final wave of Puddles to slow them all.

Guardian of the Ancient Kings’ additional healing effect does heal the Puddles, making this a pretty powerful CD for later cycles of the fight. Daybreak also works, so go into later cycles with a 2-stack Daybreak available.

Holy is a stronger spec than Disc. Cascade stops bouncing upon encountering a Contaminated Puddle. DI PoMs will bounce off the Puddles. Halo is truly ridiculous for all specs! Leap of Faith and Void Shift work on friendly Puddles.

Unleashed Fury is probably the best Talent for Contaminated Puddle healing, since you can get one to full with a UF/HS and grab that Purified Residue buff ASAP. Ascendance will heal Puddles, but AG/HTT/HST will not.

Once your Contaminated Puddles are healed to full, they will change into Purified Puddles, and will bestow all players within 12 yards with a beneficial debuff called Purified Residue. This instantly restores 25% of your mana and increases your healing by 75% for 15 seconds, and the buff stacks. You will want to be near the Contaminated Puddles when they are healed to full, so it is best to position yourself between a Puddle and the pool. Obtaining this buff is vital both to completing the Puddle-healing task – especially in later phases – and for healing through the raid-wide AoE damage at the end of the phase.

Much like healing a Contaminated Puddle to full, being near a Sha Puddle when it dies gives you a 25% damage buff to other Sha Puddles. This can be handy for Atonement healing your raid (not Puddles) during this phase.

For the very first Phase 2 Split, there will be primarily Sha Puddles, and only 3-7 Contaminated Puddles for healers to contend with. The Contaminated Puddles are distributed randomly throughout the room, so healers – especially in 10-player mode – may need to travel quite a bit in order to reach and heal them. Watch their trajectory and be prepared! Then assist your team with the Sha Puddles as much as you can.

In future Splits, the number of Sha Puddles diminishes and the number of Contaminated Puddles grows. Healers will thus want to save their strongest throughput cooldowns for later Split phases, as the more adds they can heal to full, the faster the boss will die. It is in these phases that it is most important for healers to receive the Purified Residue buff, especially in 10-player mode where the number of Puddles can be overwhelming.

Surviving Sha Puddles and Contaminated Puddles will cast Erupting Sha upon reaching the pool in the centre of the room, dealing moderate Shadow damage to all players in the raid with each explosion. This can be very deadly, very quickly, especially if players have not handled the DPS or healing tasks well. AoE throughput and damage reduction cooldowns should be coordinated to handle these moments.

Each Purified Puddle will deal about half as much Frost damage to the entire raid when it reaches the pool. It is therefore in healers’ best interests to heal up as many Contaminated Puddles as possible during the later Split phases, and stronger damage-reduction cooldowns should be saved for when there are more Contaminated Puddles than Sha Puddles, since the damage is unavoidable.

Once all the Puddles have been killed or reach the centre of the room, we are back to Phase 1, with Immerseus having 1 less Corruption per killed Sha Puddle and healed Purified Puddle. The best you can possibly do is to properly handle all 25 Puddles each time, which means the fight will end after the fourth Split phase. The fight is very rinse-and-repeat, and so long as you coordinate raid cooldowns to cover the Erupting Sha, and take care to heal as many Contaminated Puddles as possible during each Split phase, you should find it fairly simple to complete this encounter!

You will need cooldowns for: Erupting Sha (the end of Phase 2, where Sha Puddles, Contaminated Puddles, and Purified Puddles re-coalesce to respawn the boss)

Debuffs to track: Corrosive Blast (tank debuff); Purified Residue (stacking +heal debuff on yourself)

Dispels: None

Points of failure:

Tanks stand together or do not execute tank-swaps, and die to Corrosive Blast;

Players do not move out of Swirl or Sha Splash;

Players do not heal enough Contaminated Puddles or destroy enough Sha Puddles, causing the Erupting Sha ability to deal unhealable raid-wide damage.

I hope you find this information useful in your foray into the Siege of Orgrimmar. I’ll update the Contents menu with links to other bosses as I finish them. Good luck! 🙂