I'm fairly new to disc priest healing, so I've got a couple of questions. I apologize ahead of time is this is the wrong place.

first, Glyph of Holy Nova vs Glyph of Prayer of Healing, I've noticed, at least for me, that I tend to spam Holy Nova moreso than using PoH, thus it would seem a better glyph. Or am I just mistaken and shouldn't HN spam.

2nd, is there a good add-on, unit frame that shows pw:s, etc... on toons. I'm using x-perl, and though it has a shield option on it (purple outline), it doesn't seem to show it. Or is grid or healbot just completely superior?

The cookie cutter disc spec isn't maximizing the versatility of the disc spec. With current mana levels, there's no reason not to spec renew and grab the renew glyph over the flash heal glyph.

For a long time people have been hating on renew. Granted it's not as good as a druids rejuv, that doesn't make it a worthless spell at equal gear levels.

BQL
WoW Meters Online - Combatlog Replay
Sindragosa
WoW Meters Online - Combatlog Replay

Disc still came out on top for BQL, but slightly below on Sindragosa. But Sindragosa is a special case, has long periods of time where you can't actually cast (HM), with the raid dipping quite low in HP, cutting HoT overheal down 30-40%. Plus the fact of the timing of sequential Unstable Magics, and the timing of Ice tombs (tomb in phase 3 = 10-15sec down time... when the raid is in the most need of healing). But, I'd probably never go Holy for BQL, but I do switch to that for Sindragosa when we have 2 paladin's in the raid.

I would have to disagree with that statement completely (along with the original quoted post regarding the role for that fight).

Why would the disc priest NEED to be healing the tanks for the 3rd inhale phase? You've got 2-3 raid healers, sitting there wanding the boss, from a lack of raid dmg (minus the small bursts from the Vile Gas). There is no raid dmg, so all of those healers should be pouring their healing into the tanks.
The Disc priest is the only one who can effectively heal ahead of time, and do so much more effectively.
A HoT isn't going to save 10 peoples lives, from a 20k explosion and 2 AoE pulses in 3 sec, a PW:S would.

As for Rotface, there is a reason why Disc priest's are topping the healing charts for this particular encounter. Its because 95% of the dmg taken in this fight other than tank dmg, is preventable with a PW:S.

Lets face it, Disc Priest 'tank healers' were never really that strong, compared to all the other classes. Just look at Shaman/Druid healing parses for Dreamwalker. True, those are only 30 sec worth of healing with 30 seconds of downtime, but it just illustrates the gap in the actual tools each class has.
I read a thread one time from the PTR, where they tracked each classes single target HPS with PTR-Premade gear (not ideal, but ehh).
The list went as: Paladin=Druid (Almost identical HPS)>Shaman (around 10% lower)>Holy Priest (another 10-15% lower)>Disc Priest (40-45% lower than the Paladin, but not factoring absorbs, but absorbs would only add another 10-20%.... of total HPS).
The 'niche' role for the Disc priest, was simply healing bursts of tank dmg, not sustained and constant incoming dmg, that current content pretty much exclusively has.
Example:
Ever tank Vezax with a bear druid? ...
I had PW:S's EXPIRE on the MT... on Hard Mode....

Thats the only style tank dmg, where Disc priest's are actually more favorable to tank heal, than a Druid/Sham, but those don't really exist anymore, with the zonewide debuff from ICC (which is fairly standard in all higher content, tank dmg either goes from mostly physical, to almost exclusively magic, or they just hit faster..).

Why would you use a 12 sec, 10-12k HoT, when a 30sec PW:S would heal for just as much, and last 2.5x as long? Not even counting the 50-70% overheal ratio of standard HoT's, vs 0 overheal value of a PW:S.

Disc Priest's topped those same meter's, in the introduction of ICC, not after the buff came around. The only reason Holy started gaining some of its lost ground when the % Buff became active, was because Disc wasn't getting their portion of that same bonus.
Its more of a matter of Disc Priest's scaling, in general, mainly due to the fact of the huge spellpower coefficient of PW:S to spellpower. But we are getting towards the abolute extremes of gearing (kinda like DPS gets out of control at extremely high gear levels), to the point where we are exceeding blizzards original estimations, entering area's that weren't fully anticipated.

Mana is rarely an issue these days, but when working on fights like Sindragosa HM, I'd much rather have a PoH or flash heal glyph to maximize my heals outside of tombs/unchained. Go holy if you're wanting to utilize renew to its fullest advantage.

And going off what Sgat said, with DA being procced off PW:S glyph correctly now and the ICC buff, bubbles are providing an even larger buffer to any spike damage, random or consistant in fights, disc renews will not do that.

Not to mention, improved flash heal, renewed hope, and grace talents that you forfeit if using renew over flash heal.

The niche for renew in a disc spec is basically in 10 man, where you have moments where all targets are shielded or have weakened soul and PoM is on cooldown. In that case, renew is an option. In 25 man that never really happens. Which usecase did you have in mind where you would favor renew over Pw:S?

Regarding BQL: your combat log is another example why it's so difficult to rate performance based on logs. You could have done the encounter with a healer less, and that would have changed the relative amounts healed. Once there's too much healing, the disc priest always wins. You will be easily able to top your eHPS from that log if you are really challenged, but there will also be more leeway for other healers to land their heals. Holy priests are quite easily capable of exceeding effective 10k HPS on BQL.

Regarding Fenstergut, this may be another case where a disc priest can fulfill the tank healer support role perfectly, only he's more valuable as a shield spammer. I will have a look at a few more combat logs, though. There's probably more than one way to deal with that phase, depending on raid comp.

Regarding scaling: disc priests scale well, but the spellpower coefficient is only part of that. We do need that coefficient, because we scale so poorly with crit and haste (at least when we're shield spamming). The fact that most of our healing is overheal free makes our healing scale so well regarding effective healing.

It's a really interesting discussion we have here, about the role of the Disc priest in a raid. Thanks for you comments.

Just to clarify my point: I wasn't discussing the relative value of HPriest vs DPriest at all, but showing that the main assignment of a DPriest on good 25 raid should be:

1) PW:S+PoM spamming on the raid: PW:S on the players that you know will take some damage during the next 30 seconds, PoM on the tank or on a group of players that are close together and that will take some damage.
2) Assist on low health targets with Penance (very useful on tanks)
3) Assist on low health targets with FH if Penance is on CD and this target is affected by the weakened soul debuff and need to be healed immediately
4/5) *insert the use of PoH and Holy Nova here*
6) if everyone is covered by PW:S and not supposed to take dmg in the next 30 seconds and if you penance is on CD, either dps (if everyone is full hp) or heal with FH.

In 10 players raid with a tank healer (best situation):
1 to 3) same as previous
3) renew on appropriate targets (tanks for example) to fill the time gap before the end of the weakened soul debuff on the raid (usually 2 or 3 GCD)

In a 10 players raid without a tank healer, Disc being assigned to tank healing :
1) PW:S > PoM > Penance > FH(/Renew) on the tank
2) If tank is secure, use extra GCD to PW:S appropriate targets (you gain the BT haste buff as a bonus).

I don't think there is much to discuss about the utility of the DPriest covering as many players he can with is PW:S, in a 25 players raid situation. Everyone agrees, and the logs I've pointed show the evidence.
It's true that DPriest performance increases artificially when there is too much raid wipe overhealing for example when there are too many healers compared to the incoming dmg). But still if a raid leader as the choice between totally preventing dmg (via absorbs) or totally healing dmg after it occured, I'm pretty sure no one would chose the second solution, because it's less safe.

As I mentioned before, and as several fellow priests confirmed in this topic, the ICC encounters design makes the raid-PW:S-DPriest spammer shine. And I believe that there is only one encounter (Sindragosa) were the raid doesn't loose much if he doesn't have a DPriest assigned on raid healing.

I think that in the "raiding as a DPriest" we should also mention the use of Power Infusion and Pain Suppression: priority of targets, and when to use it. This is another great utility of the DPriest.

I would rather use something like PW:S > PoM > Penance > GH (with BT) > FH/Renew on the Tank as PoM and Penance don't consume BT and a 1.5s GH is pretty good.

Without even counting PW:S, a DPriest with Raidbuffed ~40% Crit would gain some ~15% HPS through Divine Aegis. And with the PW:S you gain even more HPS. If you are in 10-M and run without a tank-paladin, you could also factor in the 3% reduced dmg to the whole raid. The main Problem of Dreamwalker is that absorbs don't heal the boss. But as absorbs are what creates the DPriest niche and makes him a preferred healer that is fine imho.

You're linking to a kill where you have too much healers, considering the overheal you have.
It was being said here that this is typically the case where Disc shines on meters, because they are better to snip heals.
But shining on meters doesn't mean shining in death prevention. You're setting here at 10k max hps and 70% efficiency, where all other raid healers are at 15k and 40% efficiency. If you go with one healer less, your own effective throughput will not increase a lot, but holy priests (and shamans and druids) will be able to go up to double throughput. I can have less than 25% overheal on BQL, and holy priest have been seen over 10k effective Hps (which is more than your total hps, counting overheal).

In other words, consider the following events. A player a full health is hit by an aura ticking at 3k each 3s. He gets a shield of 12k, and a hot ticking also at 3k every 3s (for 12s). The game system will consider that the shield is fully effective and the hot fully overheal. However, from death point perspective, both would have negated the damage on their own. I agree that preventing damage is better from a death prevention point of view (due to the risk of death damage : you can't heal dead people), but the difference between 12k shield and 12k hot is not that big !
Part of the hot overheal comes from shields being applied on hotted targets.

[regarding Festergut] :
The main question is where your trouble is. If you loose people due to Pungent Blight, by all means, go with pre-shielding (and use correctly raid bubble wall / personnal cd / stance switches / etc.) . That's the most effective way to deal with it. However, if you struggle to keep your tank alive with 3 inhale stacks, then the extra health-buffer and fast heals that disc can provide can be also a huge difference. Once you have 2 paladins, you're not lacking sheer throughput to keep your tank. You're lacking effective health, and disc'tools is a lot better than holy slow great heal or little flash heal to face that problem.
I acknowledge however that healing the tank will hurt your meters, compared to pre-shielding the raid.

My main point was to say that DPriest is not a main tank healer at the 3.3.3, but rather a raid-wide damage-preventer
However since our goal here is to build a comprehensive guide about the healing Priest, I tried to give some guidelines about one possible assignment of the DPriest.

@Ramonkhan: since I don't take Divine Fury in my Disc build, and since FH receives several bonuses from the Disc talent tree, I still prefer to use FH especially when the target goes below 50% hp, to make my MT healing smoother. I think both solutions are viable, depending on the situation and the talent build. This subject has been discussed somewhere in the forum and if I remember correctly, their was no difference from a TC point of view (needs to be confirmed). The important point is the crits you get below 50%hp because of Test of Faith: massive heals, great DA proccs, and quick heal that is needed.

That actually only applies to NORMAL version of Dreamwalker. The bosses health deteriorates at a constant rate in Hard Mode, making even the strongest Disc Asborbtions to be 100% effective. The only problem with this, falls in the category of proper tracking and credit being given to the priest, and the fact that PW:S probably doesn't scale with the buff thats given from the portal phase. Granted having a Disc Priest for this encounter is actually very nice, as the downstairs tank healing role fits exactly into what the disc priest style consists of (preventing tanks from getting insta-gibbed from the blistering adds debuff, plus an abom's worms popping up, with all 12 hitting the tank simultaneously.... gibbing a bear druid with 60-70k+ in 0.5 seconds :P).
Your also leaving out the key Power Infusion on the Holy Pally/Resto Sham, that when used just before channeling Divine Hymn, can give them a 50-60% bonus to effective healing for 10-15 seconds.

I think you're comparing that report, to normal mode comparisons. I clicked the links of 5 of the 8-9fastest BQL HM 25 kills, and 3 used 6 healers, the other 2 used 5, and in both of the ones that used 5, had double Holy Pally (you either bring a paladin, or bring 2 other healers to heal both tanks, as a general rule).
So its right about equivelant to other kills.

30% bonus, to a 40% proc effect = 12%
And thats in the most ideal scenarios. As the DA proc is still only a 12 second buff. Some fights, this would be guaranteed to be used effectively (BQL/Sind/Putricide), but most other fights, DA would have 40-60% chance of expiring before being used (Deathwisper 20second frostbolt volley, Marrowgar bonestorm CD, Rotface the entire random ish encounter, Sindragosa Air phase, ect.
But ehh, again, I don't like including RNG based abilities into discussions, 30 sec long PW:S is typically longer than the majority of the major bosses ICD on ability usage, but 12 seconds isn't.

My post was an answer to 10 man healing assignments. Heroic or not, I see little point in assigning the disc priest to take portals. In normal mode, it would be ridiculous, anyway. In 10 man, I don't know which healing class or spec would be more ideal in healing the raid (and tanks) while the dreamwalker healers are in the dream (probably 2 in 10 man hc). Shields are perfect to make handling the adds safer, as is having fade available.

As for PI, of course that should be used, timed so as not to interfere with heroism/bloodlust. The same, however applies to a holy priest's glyphed GS (unless that has been nerfed to no longer work at all as opposed to just one priest in the raid). In any case, both PI and GS should be used whether the players are assigned to portals or not.

I have nothing against discussing potential roles for a discipline priest, and certainly the guide needs to say "if you are assigned to heal a tank, this is what you do:". That said, we (and as for doing the bulk of the writing now, I) need to concentrate a bit on the more relevant healing roles, as there's lots of work still to do and we don't want to finish when patch 3.9 hits, making everything obsolete. So, for now, describing a raid healing hole as well as a short treatment of tank healer support role should be enough. If we were to describe full main tank healing, then we would also have to discuss special gearing regarding this, so I'd rather leave this out - for now. Let's save that work for 3.9 where disc is supposed to be a real tank healer again. I hope this is okay for everybody.