This article is an effort to consolidate information for the new Holy Power resource for quick access. This information is current of Cataclysm Beta Build 12759, 15.08.10. Edited 16.08.10 to correct a few things
Background and UI Element
In patch 12759 a new UI 'meter' element for Holy Power was added, which in time will replace the stacking buff seen on earlier screenshots.
Holy Power is a brand new auxiliary resource for all three Paladin specs designed to add complexity and versatility to the class. Some think of it as an analogue to Runic Power or Combo Points as it shares features of both these more established mechanics.
As the Class is split between ranged caster and melee combatant models generating Holy Power differs a little between the specs. At baseline a successful Crusader Strike allows you to generate 1 Holy Power, up to a maximum of three. Once you reach level 10 the Class starts to diverge in functionality, and more options for generating Holy Power become available.
Holy Shock is Holy's specialisation bonus spell. It has a 6 sec cooldown which obviously is a guaranteed hit when used as a Heal, but will generate 1 Holy Power so long as its successfully cast. Unlike the sources of Holy Power for other specs this is probably the most fail-safe method, befitting of a healing spec.
Tower of Radiance is a Tier 6 Holy Talent, hence it is available much later in the game. It gives you a chance, dependant on the number of points you allocate to the talent and up to 100% for 3 points, to generate Holy Power when you directly heal your Beacon of Light target.
Crusader Strike is also still available, but isn't usually effective as a healer due to melee range. As there are no talents to improve it, it retains its' 4.5 sec cooldown.
Blessed Life has been changed as of build 12759. It will now cause attacks against you to generate 1 Holy Power (occurs once every 2 seconds). Feels mainly like a PvP talent unless it can also proc from encounter AoE.
In a change from the Wrath of the Lich King Paladin, Crusader Strike is available when tanking too. It tends to have a 4.5 sec effective cooldown due to a busy rotation.
Hammer of the Righteous has been retooled to generate Holy Power on successful cast as of build 12759, but not on a per-target basis. It shares a cooldown with Crusader Strike, but should be a guaranteed HP rather than based on the vagaries of Hit and Expertise.
Retribution probably has it easiest in terms of generating Holy Power in the current build. Crusader Strike is the specs bread-and-butter strike, generally used on an effective 4.5secs due to once again a busy rotation or 3 second cooldown with sufficient Haste, and still generates 1 Holy Power. Sanctity of Battle will cause Haste to reduce the cooldown of Crusader Strike (though GCD's remain a limiting factor to this effect), 3 seconds will likely be the lowest effective cooldown you can reach, though YMMV with latency).
In addition, Retribution gains the passive talent Divine Purpose in Tier 4. This allows successful casts of Judgement, Exorcism, Templar's Verdict, Divine Storm, Inquisition, Holy Wrath a 40% chance to generate 1 Holy Power, leading to a higher Holy Power generation rate than tends to be the case with Protection and Holy.
Zealotry is Retribution's Tier 7 talent. When activated, successful Crusader Strikes hits generate a full 3 applications of Holy Power. In the current build this buff lasts for 15 seconds, allowing up to 4 of these augmented Strikes, and has a 2 min cooldown.
Finally there is Hand of Light, Retributions lvl80 Mastery Effect. It imbues your Auto-attacks with an 8% chance to cause your next cast skill that consumes Holy Power be as effective as if you spent 3 Holy Power on it. If that weren't enough, said spell would also cost no Holy Power. Mastery Rating, present on gear above level 80, increases the chance of your Auto-Attacks triggering this effect.
Generating Holy Power would matter not at all unless there was something to spend it on. Thankfully, there are right now a few means of spending Holy Power, but it should be noted that every spell that uses Holy Power consumes all applications of it.
All specialisations can take advantage of a brand new spell for Cataclysm, Word of Glory. This is an instant cast direct heal which scales with Spell Power and the amount of Holy Power consumed.
If damage or threat is your thing, Inquisition if for you. This self-buff consumes Holy Power to grant you 30% increased Holy Damage, but also costs 20% base mana as well as your Holy Power. The buff lasts for 4 seconds per application of Holy Power used, 10 seconds with Retribution's Inquiry of Faith talent. Depending on gear levels, Inquisition may prove to be a sub-par use of Holy Power compared to Shield of the Righteous due to its' 12sec max duration.
None Specific to Holy, yet. Unsurprisingly however Word of Glory should be a much more effective spell for this spec.
Shield of the Righteous replaces Holy Shield as your active threat gen talent which scales according to Holy Power. Instant Cast, no cooldown, 6% base mana cost.
1 Holy Power: 20% Attack Power
2 Holy Power: 60% Attack Power
3 Holy Power: 120% Attack Power
If you take the talent Holy Shield (now a passive talent) you gain 5% block per Holy Power consumed when Shield of the Righteous or Inquisition is cast. You therefore have the option of a quick burst of threat via SotR, or the more gradual threat boost of Inquisition. Holy Shield lasts 20 seconds, regardless of the spell you choose. Reliability is once again the watch-word though, so Hit and Expertise Capping to ensure predictable Holy Power generation is a big deal.
This is where we see the rough stuff. First, there's Templar's Verdict, a new heavy hitting melee strike. The spell is currently a specialisation bonus for Retribution, and so should become available at level 10. Divine Storm by contrast is still an AoE attack scaling from weapon damage, and makes an appearance at Tier 3. It too consumes Holy Power, but isn't as effective in single-target encounters and so should only be used when there are three or more targets in range.
The damage breakdown per application of Holy Power consumed is as follows:
Holy Power Consumed Divine Storm Templar's Verdict 1 22% 55% 2 74% 125% 3 150% 225%
TV and DS are effectively mutually exclusive - use of either ability is determined by the number of enemies in range of DS.
Last but not least, there's Zealotry. Somewhat frustratingly it requires 3 applications of Holy Power to Cast, making correct timing to get the most out of this skill critical. Beta build 13189 changed Zealotry so that those 3 Holy Power aren't consumed by Zealotry itself, but this change hasn't been pushed to Live servers.
Impact on Playstyle
Holy will naturally tend to have more flexibility and mobility thanks mainly to the new talents and spells, but the Holy Power requirement requires more active resource management than is required by current design. Holy Power has also nicely added compensation in for healing the usually sub-optimal Beacon of Light target. The concept of a healing rotation starts to develop in conjunction with talents, raising the specs skill cap.
Protection gets the short end of the stick relatively speaking. Capping Hit and Expertise (i.e. eliminating dodge) is imperative to ensure constant Holy Shield up-time. It's not hard to see how this could tie a Paladin's tanking rotation into knots. Holy Power generation in single-target situations simply isn't reliable enough to warrant spending it on anything other than Holy Shield unless the amount healed by Word of Glory is significantly more than we're expecting in Tier 11 content.
It's tempting to say that Holy Power has probably had the most impact on Retribution, and I think it's quite true. However management of cooldowns remains the back-bone of the spec, and mana concerns may once again rear their head with the removal of Judgement of Wisdom. Good Ret Paladins will probably be those who can effectively weave together Crusader Strike and Templar's Verdict to maximise the damage caused when TV is cast, however the best Paladins will manage TV independent of CS and solely based on Holy Power meter. Eternal Glory (20/40% that WoG doesn't consume Holy Power) may tempt more players into using Word of Glory, but that's still an average cost of two thirds of a Templar's Verdict. The amount healed by WoG is probably critical when assessing the value of that talent, but one 'free' WoG per minute may be a better talent.
Thus far, Holy Power adds a lot of potential to the class which isn't fully exploited as yet. Zealotry also needs a review as Ret may find itself unable to use a large proportion of the extra Holy Power generated because Hand of Light and Divine Purpose procs. Another Wings-style damage cooldown seems like a shame compared to a more interesting 31pt talent.
So, a good start. Hopefully more to come as the Beta progresses.