Some tips for madness...
Atonement is decent here again, the spike dmg really works well with this spec.
- Assign a healer to heal those with the debuff, he needs to spam heal them so they're always full HP. If they're not full HP they may die, since smash removes 80% or so of your HP instantly. We used a shaman for this, a paladin is probably the best though.
- As a disc priest your immediate thoughts might be to single target heal. DON'T. This fight is all about preventing damage & keeping people topped up. You want to basically spend the entire time casting PoH while the corruption is still alive. Aegis helps to temper the damage from smash, and soaks up other raid dmg so no one goes much below 100% unless they get hit by the corruption (smash).
- Play to your strengths, the above is also true for druids - don't single target heal. Hot up the raid & soak up damage. You do need one healer to do the single target healing though, that's usually pally/shaman.
- Obviously still interweave PoM/shield/smiting into your PoH spamming
- Work out a healer CD rotation that works with your fight timings. We used the following (it's not really required on the first 3 platforms, but you may as well, it saves mana at least): (#) is platform B1 stands for blistering1, DG is divine guardian
(1) B1 DG1 SLT - B2 DG2 Bubble / tranq / PI - Tree BEFORE WE'RE ON ARM TENTACLE!!!
(2) B1 DG1 Tree - B2 DG2 SLT / PI
(3) B1 DG1 - B2 DG2 Tree / Bubble / PI
(4) SLT / DG1 / tranq bolt - B1 DG2 - B2 Bubble & personals (PI/Shaman tier)
For P2 you don't need healer CDs until the 10% bloods, for that we used tranq (you get bloods & terror at the same time here, so tranq sorts out the AOE heal req & other healers spam the tanks with single target). At the 5% bloods we used DH & tree, then SLT, then finally bubble. The hardest part in P2 healing wise is the 10% bloods, the tanks will take a crap tonne of damage, and the raid. You need to be seriously spamming your tanks like hell or they will die. Unless of course you're lucky enough to have a DK tank -.-
The most important thing is this: DO NOT WORRY ABOUT OVERHEALING on this fight (lawl 46% PoH overheal ftw?!?!
). Seriously, just spam away even if everyone is full HP. I mean provided it doesn't cause you mana problems, but it shouldn't really. I use fiend during first cataclysm, then on CD. I use HoH during 2nd fiend, and potion during 3rd. Timing things correctly I can go from 20-25% right up to 100% with fiend/hoh/rapture/archangel all timed with hoh.