Just checked, PW:S isn't scaling with spell power (nor Twin Disciplines). Absorbs 3906 damage at 85 with no talents.

Holy's mastery is now rolling. I can't figure out how it's being calculated: http://i56.tinypic.com/2i03nkx.jpg
edit: Refreshing Echoes of Light equally distributes the sum of the remaining ticks on top of new Echoes of Light. Server-client lag adds some free ticks.

Hey, are you sure ? PW:S not scaling with spellpower is a huge news ! And might be gamebreaking as well !
What you say about holy mastery makes definitely sense : that's the way Ignite or Deep Wounds are calculated on live. The new hot (or dot) is added to the remaining part of the previous one, and then, ticks values are computed base on the total amount and dot duration, and the amount slowly decreases.

To make it more clear, with an example (assuming that the hot is 10% of your direct healing, and that it last 5s (lazy to check this value) ) :

T=0 : no hot on target, you heal for 7k -> 700 hot, ticks at 140.
T=1s : 140 hot, 560 remaining.
T=1.5: new heal : 8.5k -> 850 added to the hot -> 1410 remains -> ticks at 282
T=2s : tick at 282, 1128 remains
T=3s : tick at 282, 846 remains
T=3.2s : new heal at 15k, 1500 added to the hot -> 2346 remains -> ticks at 469

and so on.

In live, there is the a lag-effect, that happens when a tick and a new event (heal, or crit for warriors) happen too close. Basically, due to the lag, the following sequence happens in the code :
- the first event reads the actual value of the dot / hot (i.e. value before both events)
- the 2nd event reads the same value;
- the first event computes the new hot / dot value, based on what it read;
- the second event does the same;
- the first event write the new correct value;
- the second event does the same, hence overwriting the first event.

In result, the first event is ignored, and the hot/dot is refreshed as if it didn't happens. But the healing / damage happened, and are taken into account for character life or mob health.
On live, this allows warriors and fire mage to have really high deep wounds / ignite ticks, larger that what they ought to be. What I explained definitely works for the case where the first event is a tick, and the second a spell crit (hence, this tick damage is not deduced from the dot, as it should, and they gain damage). I don't know if that's the case in the other order.
For mages and warriors, this won't be a big deal, because it is tied to their crits, and crit rates will be way lower in cataclysm. However, for holy priest, this is on every heal, and could happens ways more frequently (albeit less that on live for warriors, which have more criting opportunity than priest can have heals).


As for what Blizzard is trying to do: they want us to take mana into consideration, but they also don't want us to wait and do nothing because we don't have the mana. Hence, we have a heal (Heal) which we can basically infinitely sustain. Consider it as our autoattacks, or GH rank 1, if you played a healer in Vanillia / TBC. But it doesn't heal much, and won't be enough to keep our group alive. We'll need to sometimes use more expensive heals, with better hps and worst hpm, to keep every one alive. The "difficulty / challenge / interest" for healers is intended to be the decision of the right spell on the right person, based on these two constraints :
1/ enough hps to keep everyone alive (by hps, I also includes the nature of the spells (hot / mitigation / aoe, etc.);
2/ best possible hpm, such as not to be oom.

In live, we basically just consider the first case. In theory, by having a second meaningful constraint, they can lead to more interesting choices (someone is low enough to be possibly in danger : do we flash him to ensure he lives ? Do we gamble and heal with Heal, such as to keep enough mana ? ). In Wrath, mana hardly mattered, even at early tiers (yes, you could go oom. But mostly, wippes were because of lack of hps / reactivity, or lack of dps, or badly handled events. Not because healers went out of mana).

Yeah. I tested it naked, geared, with talents, and without talents. Disc's mastery isn't working at the moment (which could mean PW:S is just bugged), so the only thing that increased PW:S's absorb was the talent: Improved Power Word: Shield - Spell - World of Warcraft

I also liked GC's Heal = auto-attack analogy. It does help to understand their intentions.

Glyph changes:
Flash Heal (Prime): +10% crit chance on targets <25% health
Lightwell (Prime): +5 charges
Guardian Spirit (Prime): -30sec cooldown (sad to this one go)
SW:D (Prime): "If your Shadow Word: Death fails to kill the target at or below 25% health, your Shadow Word: Death's cooldown is instantly reset." (+ Mind Melt + Masochism = ???)
SW:P (Prime): +10% damage
Glyph of Shadow changed to Power Word: Barrier (Prime): "Increases the healing received while under the Barrier by 10%." (sounds like it affects all healers, wow)
Mass Dispel (Major): -1sec cast time
Holy Nova (Major): -0.5 gcd
Glyph of Hymn of Hope changed to Divine Accuracy (Major): +18% hit with Smite (yay for Evangelism)
Glyph of Mind Sear changed to Spirit Tap (Major): "When you kill a target with your Shadow Word: Death and yield experience or honor, you instantly receive 12% of your total mana over 12 sec."
Glyph of Mind Control changed to Psychic Horror (Major): -60sec cooldown
Psychic Scream (Major): "Causes your Psychic Scream to tremble targets in place instead of fleeing in fear, but increases the cooldown of your Psychic Scream by 3 sec."

Didn't change:
Penance (Prime)
PW:S (Prime)
Renew (Prime) (although, beta Renew is 12 sec instead of 15)
PoH (Prime)
Mind Flay (Prime)
Dispersion (Prime)
Pain Suppression (Major)
Dispel (Major) (Hmm... Dispels can be cast when there is nothing to dispel now and 3% max hp heal still works. Has a lot of potential uses, especially as max hp increases in later tiers.)
CoH (Major)
Smite (Major)
Shackle Undead (Major)

I would assume that pws not scaling with spell power is a bug as it makes both the spell and mastery 100% worthless. Make sure you file a but report to get this fixed as the spec cannot be meaningfully tested like that.

Remember way back when and the non scaling shields? that made shield a totally uncast spell and they ended up having to buff it's spell scaling from 0 to 20% to 43% as per a normal instant before people bothered to start using it. If really intentional they have just taken 6+ talents and the mastery stat and twisted them into a pretzel.

*edit*

Does anyone else have trouble finding 3 major glyphs worth taking for holy?

currently I would take PoH, renew and either shield or guardian spirit depending on who I am running with.

I've found that a good way to make people use lightwell is to work it into the strategy for a particular encounter. In halls of origination there are multiple bosses with a very strong aoe phase, so I just tell the group to go click the lightwell whenever that comes up. Most people don't pay too much attention to their own health and even if they do they're not going to look around for a lightwell, but if you give them a cue on when to use it they are likely to remember.

I had posted this on the Damage dealing forums back some time, but there was never really a response. I am hoping that some active cata-beta S-priests can answer them.

1: As a H-ICC geared Spriest, sitting at 1200+ haste, between my own CD's, raid buffs, etc.. I am casting furiously. While it's a great way to make sure that I don't dose off on a boss, it feels entirely too hectic, and I feel the need to (metaphorically) punish myself if I miss that one DoT tick, or clip that one last MF before a refresh. Going into cata, how does the priority system feel from an actual per-encounter perspective? Does it feel smoother, simply less hectic, or about the same?( I ask the last question knowing that current haste % really mean nothing, from a practical standpoint)

2: How does evangelism feel compared to shadow weaving? how well does (D)ark angel change things while it's active? I ask because right now I feel comfortable going into a fight knowing pretty solid about how I will open an encounter ( MF+MF+VT+DP...THEN swp). Will our opening sequence change up as a result of evangel?

3: I spent hours and hours all ready building talent specs strange and odd trying to come up with a spec that doesn't have holes in it that will adversely affect dps. While i know that imp inner fire is, in it's current implementation, incapable of being specced 3/3 with out losing dark angel. In the long run, do you think that this actually does need urgent fixing? will our dps suffer severely enough from it to warrant a change? or could/is it being chalked up to "quality of life"?

4: One of the things that has all ways plagued priests in PvE is the lack of access to common Crowd Control. We have shackle (situational at best....hasn't seen sustained use since Karazhan), psychic scream (at it's best, it's dangerous, at it's worst....it can wipe a raid), Mind control (a few gimmicks where this was used...razuvious in naxx, thorim in ulduar....for an achievement),and...if you spec for it... psychic horror, which is so low on the PvE CC totem pole I deign to mention it just because it is in fact there. Are priests (more or less specific to shadow) seeing more use out of the CC that we DO have? Or is CC still mostly the realm of other classes and we are basically the free-lance nukers?

5: With the new DoT refresh mechanics, the possibility of punishment from clipping seems confusing. Can we get a small, but direct clarification on how A- The new DoT refresh functions, and B- how severely does missing a refresh properly punish us compared to live raids?

There are only normal mode dungeons, but I'll try to compare:
1: Definitely much less haste. The new DoT refresh mechanic is easier/more forgiving. The priority system feels similar, but the small choices (like SW:D for mana and Archangel) add some spice.
2: Currently, Dark Evangelism and Dark Archangel are only checked on DoT cast, manual refresh, and Mind Flay refresh. That part is clunky/abusable like Shadow Weaving. A recent blue post made it sound like Mind Spike is the intended spell to use during Dark Archangel (guessing it double dips?). I've just been using it before a Shadow Orbx3 Mind Blast.
3: Improved Inner Fire has been changed: Inner Sanctum - Spell - World of Warcraft
4: Trash packs are huge and CC is very necessary for now. Other classes handled the CC, but I didn't feel useless because I was actively watching for moments to use Hymns. I did Psychic Scream for breathing room occasionally. (There is a new glyph that stops feared targets from fleeing.)
5: Manually refreshing SW:P sets the duration to full (18s) + time left before the next tick. For example (with 0% haste): refreshing at 17s sets the duration to 20s, and refreshing at a little over 3s sets the duration to a little over 18s. VT and DP work the same way. This gives a 2 to 3 sec window to refresh the DoT after the 2nd-to-last tick, instead of immediately after the last tick. The punishment for not reapplying a DoT hasn't changed: DPS loss.

Mind control works ok when it's the group's only real cc option. Pretty lackluster that our only viable cc option for the majority of dungeons completely renders us useless for its duration.

Useless depends on the capacities of the mob you control, and which one you can use.

Holy crap, a 6% run speed bonus to Inner Will is insanely good. That's 3/4ths of a boot enchant. Getting a sustained 16% bonus run speed seems pretty huge, even if it's at the cost of spell power. There's plenty of fights where I'd gladly give up Inner Fire to get into position faster.

For those curious about the interaction of the Shadow Priest talents on our spells here are the results of my testing a couple of days ago:

Shadow Word: Pain: Shadow Power * Shadowform * (SW: P Glyph + Imp. SW: P + Evangelism) * Twisted Faith * Twin Disciplines * Archangel
(It recalculates the effect of Evangelism and Archangel etc. every time it's refreshed or recast).

Devouring Plague: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Archangel
(Currently it's bugged and doesn't benefit from Evangelism)

Improved Devouring Plague: While it's obviously calculated independently of Devouring Plague itself it benefits from the same effects the same way. However it only ever has 15%/30% of *8* ticks of Devouring Plague even if haste gives you more DP ticks.

Mind Flay: Shadow Power * Shadowform * Glyph of Mind Flay * Twisted Faith * Twin Disciplines * Evangelism * Archangel
Note that currently the Glyph of Mind Flay is bugged if you have Twisted Faith. If you don't have it does the expected *1.10 damage. But if you *do* have Twisted Faith it does around *1.14.

Vampiric Touch: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Evangelism * Archangel

Mind Spike: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Archangel

Mind Blast: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Archangel

Shadow Word: Death: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Archangel
If under 25% health then: * 1.3
Also currently the SW: Death Glyph is buggy and in addition to resetting the cooldown it also still gives +10% dmg if the target is low health. In which case it would be: * 1.4

Mind Sear: Shadow Power * Shadowform * Twisted Faith * Twin Disciplines * Archangel


I've reported all the bugs of course and hopefully they will be fixed at some point.