Topic A Crazy Mage with a crazy raid priest idea.
I'm still leveling my priest but I had a quick question about all of this. I come to you guys with a background in magery. There was a time when mages would work together to abuse things like ignite rolling etc...Anyways, I don't know if this has been considered yet:
PRIEST TEAM PLAY:
Lets say you had say 2 disc priest that were completely dedicated to whoever the main tank was. These priest would go int>haste>mastery. They would completely ignore spirit 100% if possible.
Then using just the normal heal spell not using greater heal they would use Strength of Soul in unison to very quickly reduce the weakened soul time on the main tank. 4 seconds a per heal cast. if they both went haste>mastery, how quickly could they reduce the weaken soul effect? Finally consider if these 2 disc priest took turns toggling who would use PWS. They would effectively have unlimited mana in a raid environment. I believe that mastery absorption would scale better than spirit in terms of mana battery, am I crazy? Is this too hard to do? Will I make gladiator as Fire mage one day? All of these questions to be answered at some point.
I'm not sure weakened soul applies to any one healer, I think it's just a debuff thats specific to the unit it affects.
Where I'd caution the op, is that reducing the length of PW:S is only going to get you so far. PW:S' primary effect is highly underwhelming at this point, the spell gets its spot in your rotation for the secondary effects it brings - the biggest one being Rapture.
Strength of Soul's power lies in its ability to get you access to the Rapture proc closer to its 12 second cooldown instead of having to wait the full 15 seconds before Weakened Soul falls off.
Having said that, I don't see a problem in running with two Disc Priests. Two Disc priests can complement one another. The talent 'Renewed Hope' allows you access to a 10% crit bonus if WS is up on a target or if they have Grace (from you). Since you can only have Grace up on one target at a time, you can gain quicker access to that crit bonus in certain situations. You can also gain access to the T11 Spirit proc (which gives you a spirit proc anytime you use Penance on a WS-affected target) easier this way.
Also, the talent Divine Aegis now stacks and from multiple Disc priests up to a limit, that limit being 125*target's level (so 85) = 10625. So, suppose two Disc Priests use Prayer of Healing (which automatically procs DA) on the same targets. Whatever overhealing happened there notwithstanding, those 5 targets will have bigger DA bubbles than if it were one Disc priest who PoH'd them up to 10625.
If you had 3 healing priests, you'd definitely want at least 1 to be holy. (Probably 2 tbh, but 2 Discs is feasible imo.)