The wording on the Holy Mastery 18% extra healing on crit seems to show it will function like Touched by the Light's effect where 30% actually adds 45% extra healing to crits meaning 30/45/195% for TbtL, or 18/27/177% for the Holy Mastery. Edit: These seem to be base values for just putting 51 points into a tree. The Mastery stat itself will then increase the third bonus to all even more. In the case of Holydins we might even see critical heals do 200% healing instead of 150% or 177% base.

The wording might be reworked though and I noticed the Resto Shaman Mastery applies to HoT effects when Blizz said they'd specifically do it for Direct Heals. Some of the other masteries have been totally changed though since Frost Mages no longer have their "Deathfrost" Mastery affecting Fire or Arcane spells. I'm inclined to take the table with a grain of salt.

Exemplar, it's actually 76 talents we'd have, so 51 in Ret (or any other tree for anyone else) then 25 elsewhere.

I'd expect the % damage modifiers to be multiplicative as the 8.01% all damage modifier is most likely going to replace Crusade (3%/6%). The 8.01% melee crit from mastery is most likely going to replace the crit portion of Sanctity of Battle (3%) and Conviction (5%).

The Daily Blues

From the above quotes, and combined with the 51 talent point max benefit to mastery, it looks like they're limiting it to only receiving the benefit from your defining talent tree. Which makes sense if you think of it from the perspective of pure DPS classes, or really any class that has two or more talent trees devoted to the same archetype.

[e] Of course, it's alpha, subject to change, etc. I'd just be worried that adding those % modifiers from, e.g., a warrior spec'ing deep fury and then sub-speccing arms (or vice versa) would be a balancing nightmare that they'd like to avoid.

On Holy - most likely correct. At current 51 pt values, no gear: Heal crits = Heal amount * 1.08 (first bonus) * 1.5 (crit modifier) * 1.18 (third bonus) = Heal Amount * 1.91. For Holy this could actually create a nice juggling of Mastery vs Crit on gear. More Mastery makes getting a crit better, so Crit Rating becomes more desirable. Assuming minimal overheal (somewhat a Cata goal?) then as you crit more, Mastery becomes desireable to increase heal size.

Prot could have similar synergies. If a block reduces damage by X% and you block Y% of the time, effective mitigation is X * Y. As Mastery increases you block more (Y increases), you mitigate further (Z is better). Attacks, blocked or not, are then mitigated by the first bonus (call it Z). So average damage becomes: damage * (1 - X*Y) * (1-Z)

Paladin remain multipliers on multipliers. This leads to the old scaling worries - it's non-linear. As bonuses accrue damage/healing/mitigation increase faster than an outside view might expect.

As Glutton said, things aren't even set in Etchasketch at this point, much less Stone. But there are a lot of multipliers going out to a lot of classes. If Blizzard can manage the balance dance in the first tier, the next tier could cause disparity as all classes do not scale equally (in any of the roles). Classes/specs with more multipliers would increase faster than those with few/no multipliers.

I wonder if they ever internally generate stats for the 2nd tier of gear, equip items with placeholder names and check the balance.

While I understand that they'd want to model the scaling strictly from point X (entry raid tier gear) to point Y (end-game raid tier gear), I never understood why they didn't attempt to extrapolate further. It seems a little short-sighted. There are many external effects to scaling outside of accidentally adding an extra tier of loot (e.g. the ICC buff) that can make things go out of whack.

We've seen the system go wrong in the past (referring to, for example, the 1400 DPS Warrior on Patchwerk back in vanilla, the high mage dps available via a certain set of trinkets and set bonuses, and the rogue who got 102.5 dodge in TBC). I would have honestly thought they would have taken each class and seen what happens when you simply boost a given stat or set of stats as high as it's possible with the right combination of gear and talents to make sure nothing breaks.

It seems that they've escaped this problem in WotLK, but I fear it's mostly due to the fact that there are just so many tiers of gear, large iLvl gaps between each tier and, for the most part, the fact that iLvl is the only indication of whether an item is better (coupled with heavy diminishing returns on certain stats). Prior to WotlK I felt you could pick-and-choose your gear a lot more than you can now. (Now you have the choice between a tier item or non-tier item for most slots.)

Giving themselves a reasonable amount of breathing room on the top end of the scale while keeping all classes scaling linearly and roughly equivalently should, in my opinion, be what they should strive for while modelling class scaling for each new expansion.

The problem is that not all abilities scale linearly to the same degree, and this is especially true when you want to 'experiment' with special effects like TAJ, shadowmourne proc, etc.

Early in Wotlk, we had CS > J priorities. All through Wotlk the actual mechanic (FSCS) hasn't changed, although changes in gear has caused the priorities to change.

Trying to balance all classes and all specs to do 'more or less' the same DPS, healing and tanking is a tough nut to crack as it is with the narrow gear options they are assuming now. Not all abilities scale off the same stats in the same way afterall. This means that somewhere along the line, if you keep adding more and more stats, something is going to go out of whack.

With the 10/25 split and the normal/heroic split, and the need to make gear upgrades valuable enough (read: make players pay their subs to get it), blizzard ended up having several tiers more than they had worked their balance around. So some abilities for some classes with specific gearing combo's end up deviating enough from the balance medium to end up being OP (or UP).

Just scaling everything linearly would be possible, but it would also be a lot less 'interesting' as blizzard points out themselves often enough. Just remove all stats from gear and just add a single stat : "increases your damage, healing, mitigation and survival by X%".
Making all abilities scale linearly would end up being just that, even if they ended up obfuscating it behind stats such as strength/agility etc it would still loose a lot of what makes epics fun today.

GC confirmed yesterday what I posted earlier, that you only get mastery bonuses from your spec defining tree.
Source

So there's no mastery-based reason to subspec into prot as opposed to holy.

While that may be true in a small way, and correct me if I'm wrong, but the majority of the changes to the FCFS have little to do with the level of stats on gear themselves, but more so set bonuses and changes to mechanics. For instance, the loss of seal of blood and it's replacement with the new seal of vengeance, as they do differing amounts of damage in both seal procs and judgements, the changes to CS, which increased it's value if used on cooldown, but decreased it if pushed to the 4.5s cd that it usually sees. Any set bonuses that modify only a single skill attack, make that attack more valuable in the rotation. So, while the basic idea of FCFS has not changed, the priority order has, but due to these things rather than stats from gear, and while stats could cause a change to the rotation at certain levels of gear, it has much less of an impact.

Our scaling is much more linear than implied, and while I am unsure about other specs, I would find it difficult to believe that most are not more or less similar. The problem is introduced with the set bonuses (for the fun aspect), which cause the scaling to deter from it's relatively linear path and/or changes to spells, abilities, or talents, let alone specialty items.

World Of Warcraft: Cataclysm Video Game, Big Changes Interview HD | Game Trailers & Videos | GameTrailers.com

This isn't anything concrete, but our old friend Ghostcrawler acknowledges when speaking on class changes for Cata that both Protection and Retribution Paladins "don't have enough kind of going on" in this video around the 2:50 mark; I only post this because he makes similar marks in regards to the Shaman, Hunter, and Warlock changes.

It may be telling that we have a little more coming our way than, at least I, originally thought.

Since the NDA has been lifted, here's a comprehensive list of Retribution relevant changes in the Cataclysm closed beta that I've been able to observe so far. Retribution's proper Cataclysm talent and ability revamp hasn't occurred yet, although I would expect it within the next month.

Consecration

• Can now crit at 150% damage. Uses spell crit table.
• Damage calculation (per tick) has been decreased from 4% of AP and SP to 2% of AP and SP.
• Duration has been increased from 8 seconds to 15 seconds. Cooldown remains 8 seconds.

Crusader Strike

• Crusader Strike is now a baseline ability.
• Damage calculation has been increased from 75% to 100% of weapon damage.
• Improved Crusader Strike increases the damage done by 10%. Presumably a placeholder; the talent is broken/bugged and no effect on Crusader Strike damage when talented.

Divine Storm

• Damage calculation has been decreased from 110% to 55% of weapon damage.
• No longer procs seals.
• The target cap of 4 has been removed; now can hit an unlimited amount of targets.

Exorcism

• Damage calculation and cooldown are unchanged relative to live.

Hammer of Wrath

• Damage calculation and cooldown are unchanged relative to live.

Hand of Reckoning

• Damage calculation and cooldown are unchanged relative to live.
• Can now proc seals. Presumably a bug.

Holy Shock

• Holy Shock is now a baseline ability.
• Damage currently scales with 43% of SP and 0% of AP; 6 second cooldown.
• Healing Light (Tier 2 talent, Holy tree) now increases the damage of Holy Shock by 4/8/12%.
• Sanctified Light (increases Holy Shock critical strike chance by 5/10/15%) has been moved from Tier 5 Holy to Tier 4 Holy. At level 85 it may be a viable DPS talent if the Retribution tree remains bare bones.

Holy Wrath

• Damage calculation and cooldown are unchanged relative to live.

Holy Vengeance

• Can now crit at 150% damage. Uses melee crit table.
• Damage calculation is unchanged relative to live.

Judgement

• Seals of the Pure now increases the damage of Judgement of Command/Light/Wisdom/Justice.
• Sanctified Light (increases Judgement critical strike by chance 5/10/15%) has been moved from Tier 5 Holy to Tier 4 Holy. At level 85 it may be a viable DPS talent if the Retribution tree remains bare bones.
• The Judgement of Light healing debuff has been decreased from 2% to 1% of maximum HP.

Seals

• Seals of the Pure now increases the damage of Seal of Command.
• Divine Storm no longer procs seals.

Righteous Vengeance

• Can now crit at 150% damage. Uses melee crit table.
• Damage calculation is unchanged relative to live.

General

• All partial resists on spells have been removed.
• Swift Retribution is now identical to Windfury or Icy Talons (20% melee and ranged haste.) All 3% haste buffs have been eliminated.
• Vindication and all other AP debuffs now decrease physical damage taken by 10%.
• Heart of the Crusader and all other 3% crit debuffs are slated for removal.
• Blessing of Might has been merged with Blessing of Wisdom. All static AP buffs have been eliminated. Provides 10% AP and 249 MP5. One cast now buffs all party/raid members.
• Blessing of Kings now increases AGI, INT, STA, and STR by 5% and all magical resistances by 214. One cast now buffs all party/raid members.
• Fire, Frost, and Shadow Auras have been merged into a single Resistance Aura. Doesn't stack with Blessing of Kings' resistance component.
• Retribution Aura provides 40% melee haste while all other auras provide 20% melee haste when Swift Retribution is talented. Presumably a bug.
• Dragonkin has been added as an additional race for the conditional portion of the Crusade talent.

It doesn't overlap. Also, in the default UI there is a new icon near your character while consecrate is ticking (with a timer). If you right-click it, the consecrate is "killed".

From my quick testing on the target dummy yesterday, this appears to be fixed now. I could be wrong though, this was a quick cycle of tests before my raid last night.

Also to reinforce what Glutton/Bluedeep said, Holy Shock is actually quite substantial right now. This is obviously in part due to the 3rd tier retribution mastery (+% holy damage), but it's still a little surprising to me. With a 6 second cooldown and range, it doesn't seem to fit with retribution. I guess we'll have to see how they handle it after the retribution revamp.