Immerseus, Keeping it Together
Immerseus is a great first encounter to start the raid zones. There is certainly a lot going on, but it sets the tone for the rest of the raid pretty well I think. Immerseus is the animated embodiment of the sorrow felt at the corruption of the life giving waters of the Vale of Eternal Blossoms, and it is your job to cleanse the waters. The fight is divided into two phases that repeat themselves until the boss is completely cleansed, when the boss is in one piece and when the boss splits up.
When the boss is together, there is numerous abilities to watch out for. The good news is that most of it is watching your feet and standing, well, not in the bad. Swirl is the resurrection of a good old favorite raid mechanic of mine from back in the days of Burning Crusade, Geyser. Though this version comes with a little bit of a twist. Swirl causes Immersues to summon spouts of water to erupt from the ground, as well as him spinning around in a semi circle also shooting out a jet of water. If you're hit by either, you take a decent chunk of damage and get knocked back. The ground swirls move around, so you'll have to watch not only the boss and his facing, but also where you are standing. The good thing, or at least as far as I've found, is that as a shaman you won't get insta-killled if you happen to make use of your Stone Bulwark Totem. I've actually found myself stuck in a weird arc having to choose between damage on the ground and having to ride the wave, so to speak. SBT proved to be enough to keep the damage from killing me, and giving myself enough time to heal up and get back into the fight.
The other major thing to watch out for is Sha Bolt, which deals a bunch of shadow damage and leaves a pool of death on the ground below you once you've been targeted. You need to make note of where these are because running through them will deal damage to you. The other reason to make note of where they are is because when the bosses health dips to the point of him splitting up, he will draw all of the puddles back into the center point. As they move, they will deal damage to you if they pass through you. The good news is, that they are pretty easy to avoid, especially when you make use of Ghost Wolf to move around them.
Falling to Pieces
GW is also important because in the split phase, phase 2, you're going to need to get a hustle on and move to wherever there is a Contaminated Puddle. These puddles must be healed to full, and as a healer with access to an instant cast travel form, you should make it a point to get the puddles furthest away from the group. Healing them is very important, because the globs will move towards the center puddle to reform Immerseus. For every puddle that gets healed to full, it will remove a unit of corruption from the reformed Immerseus. That is after all the name of the game and encounter, and this is a part resto shaman are actually pretty good at.
As an added bonus, for every puddle that gets healed to full, it will give a Purified Residue, which will restore 25% of your mana, and increase your healing done by 75% if you are withing 12 yards of it when it reaches full. As you heal the globs, they will begin to move slower, giving you more time until it hits the center. Here is a place where you want to make use of Spiritwalker's Grace. Moving while healing the globs will keep you within range of them to receive the healing buff, and that is pretty important. Chain Heal is also your friend here, as I found out this week, it will chain between globs if they are close enough together. The simple fact that it is a circular room and they are moving towards the center, well it means that they will be close enough to hit multiple globs as the fight goes on, and more contaminated puddles are spawned. Ancestral Swiftness is also very useful here, especially if you need to land a Greater Healing Wave right before a puddle hits the middle. While Healing Rain doesn't seem to target the globs, we certainly have the mobility, albeit temporary, to land huge heals while on the go which is really nice for this phase.
The final part to really take note of is Erupting Sha, which triggers in phase 2 whenever a glob reaches Immerseus. This is raid wide damage that is based off of how many corrupted and purified globs reach him. Save your Healing Tide Totem and even your Ascendance for this part, to make sure you get that raid healing out. Healing Stream Totem is also good here to make sure the people close to dying are getting that extra healing love. After that, it's just a rinse and repeat until the boss has no more corruption, and you get to move deeper into the recesses beneath the Vale. It's a great first encounter, with a lot of different mechanics to observe without being nearly as overwhelming or hectic as some of the fights in Throne of Thunder. I feel like it really has a good balance to it, and it really is a fantastic boss battle to begin the new tier with.
Totem Talk: Restoration lends you advice on healing groups, DK tanks and heroics and mana concerns in today's endgame -- or take a break and look back at the rise of the resto shaman. Happy healing, and may your mana be plentiful!