[Updated: Added Heroic section and a note about Spectral Guise to Thok.]
MalkorokSo, heroic Tortos was fun. Malkorok brings H Tortos mechanics to normal mode raiders. Basically, most of the fight, all heals convert to an absorb barrier on everyone, which you have to keep stacked so no one ever loses any HP. If they do, you'll have a chance to heal them once or twice during the fight: in the Blood Rage phase.
Track the Ancient Barrier
You won't be able to heal this fight without Weak, (normal) and Strong Ancient Barrier debuffs on your raid frames (or some kind of cool addon graphically showing absorb stacks - if anyone knows of one, please comment). Keep people's barrier stacked up, particularly if they've already lost some HP.
Atonement actually works!
So, Blizzard seems to have done some unique tinkering with smart heals just for this fight. All smart heals, including Atonement heal the person with the lowest (HP + ancient barrier). This means that assuming nobody has dramatically lower HP than everyone else, it will actually heal people with low barrier stacks. Neat!
Divine Aegis actually works!
Contrary to popular opinion, Holy isn't definitively better here. Divine Aegis still procs properly from crit heals, and still absorbs hits - such as the constant 15k DPS DoT on everybody. Divine Aegis, Spirit Shell, and PW:S will all work to prevent hits from depleting ancient barrier. Hit people soaking the Imploding Energy with a PW:S so their barriers don't deplete as much.
Levitate cancels the fall damage.
2700 mana for a ~300k damage prevention on a target that's already likely to be low on absorbs? Yes please. Speaking of which, the boss casts one of those immediately after the fight begins. Start the pull with Spirit Shell stacked up so someone doesn't get shot to 20% HP immediately.
Pain Suppression + PW:S can cover fuck-ups.
Someone (like you) about to get owned by Breath of Y'shaarj or something? These two defensive abilities can save someone, even if their ancient barrier wasn't stacked. If it was, they might not even lose any HP.
Use PW:Barrier in Blood Rage phase.
You can't be stacked in the other phase, so there's no better time to use it.
Balls. Balls, everywhere. 40 balls of death will form per minute. These balls completely strip the target of ancient barrier, and then deal 150k damage on top. That sounds bad (and it is) but you can't simply avoid them all fight. The room will get overrun. People are going to need to intentionally clean them up. This can be done more-or-less safely in Blood Rage phase, but you might not want to wait that long to start, either. While some players like me can seemingly dance through a thick jungle of balls with impunity, probably someone in your raid won't be so graceful.
Players with immunities or near-immunities, like Shadow Priests, Monks, Rogues, Death Knights and Paladins should intentionally soak a bunch of balls when their cooldown is up. Failing that, you can have people intentionally soak orbs when they have traditional absorbs on them, such as Spirit Shell or PW:S. Be sure to hit them with heavy healing afterwards to get their barrier back up. Try not to have people collecting orbs before a big damage burst, like the Seismic Slam cooldown.
For blood rage phase, we had the raid spread out, both to counter the new and improved Displaced Energy, which roots its targets, and for people to soak up all the balls around the room. Your raid is likely to be fairly beaten up entering this phase, try to stack Divine Aegis as it begins so the first tick of Displaced Energy doesn't oneshot someone. The tanks will get absolutely destroyed tanking the boss with just the two of them in melee, so have a cooldown rotation planned in advance, and spam heal the living crap out of them.
Spoils of PandariaYou'd expect a fight against a giant treasure chest and a room full of loot to be a loot pinata. It's not. This fight is a glorious AoE clusterf*ck with a tight berserk timer on heroic.
DPS the things.
Healing this fight is fairly easy, but you still need two healers because of positioning issues. Make it more like two half-healers by making heavy use of Atonement. Even on heroic where healing is fairly difficult, your damage output will likely be necessary to beat berserk timer.
On that note, skip Cascade.
It's not really needed, as the positioning doesn't demand it, and it can't do both healing and damage together. Yuck. Halo and Divine Star both work well, and which to use will depend on how your group moves.
Abuse the healer buff.
So, that buff you get? The one that's going to do 50% of your damage? Make sure you abuse the hell out of it. It will fire a wave in the direction you're facing every ~8-12 seconds. Make sure you're facing at a thick crowd of enemies. It'll deal a positively staggering amount of damage to enemies it washes over, and a decent amount of healing to players. On heroic, the damage goes from "a bit nuts" to "crazy as a loon," so it's even more important.
Mass Dispel the Residue.
While your DPS should interrupt it, or chain-stun the healer, or something... well, let's just say that even in a heroic guild it seems that asking them to do what they should is asking too much. To be fair, it is a bit of a hard fight. Fortunately, you can clean up their mess. The HoT heals a whopping 600k per target over its duration, so it's well worth dispelling. On heroic, that rises to 1.2M.
Prayer of Mending is broken.
For some reason, Prayer of Mending always vanishes shortly after application (with no healing). Seems like a bug. Check if it has been fixed, but if not, looks like we can't use it here.
Heroic turns the DPS requirements up to 11 (and the healing up to like 8.) Damage output is even more important than on normal, but you'll occasionally be forced to stop Atonement in favor of real heals. Still, the difference between a Disc priest using Atonement until forced to stop, vs. a Disc priest not using Atonement is like night and day. The extra damage you do will prevent a crapton of incoming damage in the long run, and also will probably be needed to beat berserk timer at all.
The large boxes are particularly dangerous on heroic. The large mogu deal massive bursts of magic damage at regular, infrequent intervals. Don't panic if you see one of these blasts drop your shaman to 20%, you may actually have enough time before the next blast for Atonement to top everyone up. They gain damage based on the number of summoned statues alive, so make sure those are being cleaned up. Halo, Divine Star and the healer buff can all help with that.
The large mantid, on the other hand, deal steady DoT damage to the entire group. Given that you'll be facing ~300k incoming DPS (and have to move for Set to Blow) you'll probably need to actually heal. PoM would be awesome here... if it worked. Unfortunately, it seems to be bugged (ha!) in this room. Request healing cooldowns from your DPS, if you have any. If you have the healer buff, pointing it through your group can actually cover the extra healing needed on its own.
Thok the BloodthirstyTwo phase enter. One phase leave. The fight has two phases: a stack-up-and-AoE-heal phase, and a run-around-and-kite phase. Phase 1 ends when you fall far enough behind on healing, so if your healing is good enough, you can actually camp out in phase 1 more-or-less indefinitely.
Many interrupts, handle it!
Each of Thok's Deafening Screeches will deal a bunch of raid damage and interrupt all spell casting. Early in the phase, it's no problem to skip a spell right as it goes off. As the phase wears on, however, they get faster and faster. Familiarize yourself with your abilities which can allow you to heal while being spam-interrupted.
Divine Star is king.
Sure, it'll be useless in phase 2, but it is god mode in phase 1. Burn it on cooldown for the massive heals it provides. Being instant, it can be used during interrupts. Yay!
PoM, PW:S, and Renew. They work.
All three are instant, so all three can be used during the interrupts. I've listed them in order of how good they are to use.
Inner Focus: it does more than just summon a crit.
...it also makes you immune to interrupts long enough to cast two Prayers of Healing. Use it late in phase 1.
Burn your cooldowns in phase 1.
There won't be anything to use them on in phase 2. I recommend Pain Suppression on the tank as the interrupts start ramping up, and Barrier on the raid shortly thereafter. You might not get much use out of the other talents, so Power Infusion too - if people aren't dropping low enough to trigger Twist of Fate.
Atonement fixes range issues in phase 2.
Your raid will be scattered to the four winds during the second phase. Atonement off the boss should cover the majority of the room.
Thok is fast. Feathers can help.
I'm a die-hard Body and Soul fan, but this fight is one of the times where I routinely wish I was specced Angelic Feather. Thok can be seriously fast, and the one PW:S you can use just doesn't cut it.
Spectral Guise actually has a use.
Spectral Guise can force Thok to stop chasing you. Use this as a last resort, because he will immediately turn around and go shooting back towards the rest of the raid.
Heroic mode is weird. This is the only time I recommend reforging into Haste. 30% haste or so will allow you to reliably fit a Prayer of Healing in between each Deafening Screech.
The differences on Heroic are:
- Deafening Screech (and the other sources of raid damage) hits dramatically harder - a whopping 470k physical (ignores armor) on 10man heroic.
- The boss has a crapton more health (and heals when he eats anything - including the mandatory NPCs), and as such, berserk timer is rather tight; you'll need to stretch out each of the phases as long as you can in order to have enough time to kill him.
- 30 stacks of the Deafening Screech buff is an instant raid wipe. Transition before then.
- During the second, third and fourth main phases, trash will spawn. Second phase, it's the vampire bats, third, it's the yeti, and fourth, it's... something else. We haven't made it that far yet.