This rather large troll is quite a bit of fun, and is actually a surprisingly resto shaman friendly fight. The fight is divided into three parts really. First is the real realm, or boss realm. Here the boss will be tanked as normal, and in every version of the fight I've seen, the raid will be grouped up near or behind the boss. This is good news for you, because you can make a lot of use out of Chain Heal, and Healing Rain. In this plane, the main source of damage to the raid is going to come from Shadowy Minions casting Spiritual Grasp and Shadow Bolt. The longer the adds are left alive, the more damage will be going out. This is a variable that your raid can control as they grow more confident with the encounter. The other source of damage is going to come from Voodoo Dolls, where Gara'jal will select a number of players and turn them into Voodoo Dolls. While under the effect of this spell, all damage taken by the victim will be copied to all other Voodoo Dolls in the raid. On 10-man this is 3 total players and in 25-man this is 4 total players. This is something that you will need to pay attention to, because it can cause some pretty big spikes in damage if adds aren't being handled quickly enough. Healing Stream Totem can help make it a little less horrible to heal through, and if you're particularly in a bind and everyone is grouped up you can drop Spirit Link Totem to keep the Dolls alive. Stone Bulwark totem is really handy here to help absorb some of the incoming damage on yourself as well, and I found it quite useful for staying alive.
The second part of the fight takes place in the spirit world. Throughout the fight, Gara'jal will periodically throw out a Spirit Totem that will allow players to Cross Over by either right clicking it, or destroying it depending on your raid difficulty. Players will lose a portion of their life when they cross over. While in this realm, you can actually take the fight to the Shadowy Minions. You only have 30 seconds once you get down there to use the Return Soul ability, however, or you will die. Healers will have to go down with the groups of DPS that dispatch the minions, because the only way to get the return soul ability to show up is to be healed to 100% health. Greater Healing Wave with our Mastery is a great way to get people topped off so that their action buttons show up quickly. As an added bonus, healers also energize their raid companions through a Spiritual Innervation. Each class gets a different buff, but it can only be granted by a healer and through healing players in the spirit world to full. As you continue to heal, the buff stacks. This is important because players will have to receive the buff in order to complete the encounter successfully.
At 20% health, Gara'jal will go into a Frenzy, gaining an additional 25% haste and inflicting 10% additional damage. At this point, he will also stop summoning spirit totems, so you won't be able to go into spirit world for buffs or to handle adds. Hero/Lust is usually saved for this part of the encounter, and I find that it's the ideal time for Healing Tide Totem and some Ascendance. It's a fun fight that just requires timing and execution, and tends to play well to shaman healing strengths.
The Kings are Dead, Long Live the Kings
This if a four part fight, really, with each of the Mogu kings activating in sequence with only one of the Kings attacking the players until it is defeated and then next one activates. The cool part is, that even after you defeat one of the kings, it will stick around in ghost form and still contribute one of their abilities into the fight periodically.
Qiang the Merciless is a military commander, and he has three main abilities that raid groups will be watching out for. First, is Massive Attacks, which inflicts a ton of damage that is split among everyone hit by it. Because of this, you will be grouped up on top of the tank. Take full advantage of this with your healing rains and chain heals to pound out that group healing. Next is Annihilate, which deals damage in a cone in whichever direction the boss is facing and is highlighted by a bunch of rubble coming up from the ground. You can't really heal or mitigate this, so just move out of the way. Lastly is Flanking Orders, in which Qiang will activate one of the rows of warriors that stand sentinel around the encounter area. They will walk in a straight line dealing damage to anything in front of them. If you find yourself cut off from the raid group because you rand the wrong way, or just got split from the raid group, Riptide combined with Spiritwalker's Grace and some mobile healing will help you keep the group up while you move back into position. This ability will persist throughout the fight
Subetai the Swift really only has a few tricks up his sleeve. Volley will do a cone attack damaging anyone in front of him. If you are caught, pop your defensive cooldowns like SBT or Astral Shift then Ghost Wolf and just run out of the effect. This boss will periodically cast Rain of Arrows in an area, and anyone caught inside of it will not only take damage, but will get pinned by Pinning Arrow which will inflict periodic damage and root the player in place. Help break victims out with some Lightning Bolts and in the process get some of your mana back from Glyph of Telluric Currents. Lastly is Pillage, where the boss will spin in a flurry of motion stealing a players possessions, reducing damage and healing done by 50% and armor by 50%. Simply run away from him if you happen to be in his circle. This effect persists throughout the fight.
Zian of the Endless Shadow is a caster boss that will blast random raid members with Charged Shadows and Shadow Blasts. This tends to be a spread out phase, so expect to rely heavily on Riptide and your single target heals to keep people alive. When you see someone get blasted with charged shadows, depending on their health, don't be afraid to pop a Nature's Swiftness with a GHW to top people off or stabilize. Undying Shadows will target a random player and summon a skull creature that will follow them around dealing periodic damage to that player and anyone within 10 yards. Make sure you give players targeted by it some attention, and if you yourself are targeted by it, ghost wolf and drag it out of the raid quickly so it can be killed. This ability will persist throughout the fight.
Meng the Demented is a boss in which your raid can quite literally kill themselves. Maddening Shout will cause raid wide damage and cause every player to become hostile to one another. Your raid group will have to deal damage to one another to regain their sanity. Most strats call for the raid groups to group up, so take advantage of this by laying down a HR on the stacking point as people are running in and chain healing as soon as the MC is dropped. This effect will persist throughout the fight. He will also swap between Crazed, in which his damage output continues to increase, and Cowardice. Cowardice is the one you need to watch out for, as when he is under that effect he will reflect an increasing amount of damage done to him back at the player inflicting it. An overzealous DPS can quite literally break themselves upon the boss, so just watch players healths and be mindful of health drops. HST helps a ton here because it will always target the lowest person, and help you stabilize them.
For the spirit kings, there is a lot of movement, a lot of self preservation, and generally a lot going on. Between spreading out and collapsing you're going to be switching gears a lot. Consider loading Call of the Elements for this fight so you can reset HST and defensive cooldowns like astral shift or stone bulwark totem, though I highly recommend using SBT. Also, consider Glyph of Chaining for this fight. For most of the fight people are going to be running around, having a 4 second cooldown on Chain Heal is not so bad when you consider you are effectively doubling the jump range. Your Chain Heal will be more likely to complete all of the jumps with this glyph instead of potentially losing jumps from people not being in range. Glyph of Spiritwalker's Grace is also not a bad idea for when you need to run and gun.
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!