Okay, now that that's out of the way, let's talk about "healing space." This is not an alternate zone that healers live in, perhaps like the Emerald Dream area in the Valthiria Dreamwalker encounter. This maps out where each healer excels, when able to do what their class abilities optimally allow for, to create maximum synergy between the healers in your team.
This is much more crucial in twenty five man encounters, when you have more healers and significantly more overlap. It does happen more often in ten man encounters that healers get isolated more on their own healing islands, in which case you cannot "specialize" as much. However, as you push into heroic modes, even ten man raids are well-advised to try to organize the encounters such that all the healers you're using can cover all the same targets (everyone). This is not always possible but, when it is, that's where heal space analysis is valuable.
The long and the short of it is that if two or three healers can cover the same targets, you maximize their effectiveness by A. making sure the two or more healers have complimentary powers and B. having each healer bias their spell usage toward specialization.
So what heal space does each class inhabit? Let's take a look.
Note: The next four sections are a quick look at what constitutes the core of each healing class (and spec, in the case of priests). If you would find a run-down of these class-specs dull, skip past the sections with class headings. None of those sections contain theory, just my views on what (essentially) makes each class-spec unique. That "healing world view" is important to the theory that comes later, of course, but I don't believe my healing world view is controversial.
For the last (large number here) tiers, druids have been the reigning overall healing throughput champions. With their "creeping heals" (my term for healing that's always creeping upwards, everywhere, all the time), they're almost like the inverse of a damage aura...they provide a healing aura (as it feels from the outside, this is in no way to suggest that it's passive on their end) as everyone's life bars are always moving upwards thanks to them. They can Rejuvenation blanket when everyone's taking AoE damage, Wild Growth on cooldown, Swiftmend to create a healing circle under a group of people and keep potent HoTs (the aforemention Rejuvenation and Lifebloom) rolling on the tank(s).
And then, of course, there's always the raid healing bomb of Tranquility lurking.
The reason druids have been such potent raid healers is because they're not provided any absorption or mitigation abilities (leaving aside the personal cooldown, Barkskin, which is of only niche value to a restoration druid). Their contribution is entirely wrapped up in moving life bars, so they move them a lot.
While they can use direct heals to keep someone, like a tank, alive through continuous damage, it's not where they excel and it's not the optimal use of their mana. "Optimal" is the crucial word for this analysis, since we're trying to maximize a healing team.
For the last four or so tiers, at least, paladins have been somewhere between very strong and broken-strong (ICC days) as tank healers. They've been given some new tools in Cataclysm (notably, Holy Radiance and Light of Dawn), but neither has changed the fact that the bulk of their work is done with strong single-target throughput. Their healing space will probably have to be re-evaluated once patch 4.3 arrives, due to the major changes to how Holy Radiance will work.
Holy Radiance (thus far) has been constrained by a cooldown, making it unspammable, and Light of Dawn is a holy power release, so it's also unspammable, since they need to build up holy power in between usages.
That leaves paladins the most beholden to the "Three True Heals" model that Blizzard has tried to build into every healing class (with varying levels of reliance across classes). Since their "quick, mid-level heal" Flash of Light is not generally considered a good use of mana, they end up heavily reliant on four spells with a heavy emphasis on the first two (being the ones without a cooldown or holy power requirement): Holy Light, Divine Light, Holy Shock and Word of Glory.
So direct heals are what paladins will be dealing in, largely.
Shamans have an interesting concept. The majority of their healing is direct, though they also use an area HoT (Healing Rain) and a more traditional HoT that procs from one of their main direct heals (Riptide).
What makes shamans interesting is their mastery, Deep Healing. The upshot of their mastery is that the lower health their healing targets, the more powerful their healing spells are.
So shamans are a mixture between direct healing and healing over time, with potency inversely related to the health of their target.
Priests come in two flavors, of course. There is the Discipline flavor and the non-Discipline flavor (I kid, I know that one of the healing trees is named Holy, even if Blizzard doesn't).
Discipline priests have always had a unique mechanic (which holy paladins have recently infringed upon with their mastery, but not very successfully except in niche cases) known as absorption. These are shields that absorb some of the incoming damage before it can affect the player. Shields are the centerpiece of the discipline spec. And while discipline priests (like all healers) have an assortment of direct heals, the other thing they have which is more or less unique to them is mitigation. This is similar to absorption, in that it prevents damage rather than healing it, but rather than absorbing it, it reduces the degree of the damage by a percentage basis. So instead of absorbing 45,000 damage, it will reduce the incoming damage by 10%. One of their signature mitigation spells is a tank cooldown, Pain Suppression.
Holy priests on the other hand do very little absorbing and mitigation. They are more similar to druids in that they use healing over time and direct heals to do lots of healing over the encounter time. While druids bias more toward HoTs, holy priests bias more toward direct heals. Unlike druids, holy priests do have a potent tank cooldown, Guardian Spirit. As you might notice, Guardian Spirit is kind of the reverse doppelgänger of Pain Suppression. While Pain Suppression mitigates damage by 40% on a target, Guardian Spirit allows for 40% more healing on the target. Guardian Spirit has the added benefit of preventing a death, which does make it a bit more powerful but also compensates for prevented damage being less risky than healing damage after the fact, a factor that makes damage mitigation more powerful than a healing boost.
Healing, Economics...Same Thing
If all of that was a fairly old hat recap of the healing class-specs, I apologize. In terms of structure, I felt it was important that we establish what each healer is doing at his/her core before we start parceling out territory in the healing universe.
The central concept of healing space is this: While every healer can do a variety of things and fill any role, especially direct healing of all the things, the highest efficiency is achieved by each healer focusing on the things they do best and avoiding the things they don't do as well as another, even if they can do it well. If you've studied economics, this should be a pretty familiar idea, because it's mirrored perfectly by the idea of Comparative Advantage. By specializing in what you do best (rather than doing everything you do decently), you increase the efficiency of your team. To make the parallel to the economic theory, if you analogize your healing team to a world economy, your healers are trading products (throughput) for currency (mana efficiency) with each other.
The economic theory of comparative advantage is wonderfully counter-intuitive to most people when they first encounter it. It generally isn't an immediately obvious idea that, even if you're good at a number of things, if you exist in a world with potential partners who do anything better or worse than you you're better off specializing rather than doing everything you're good at.
Blizzard made sure every healing class can fulfill any role competently with the advent of Cataclysm, because they didn't want raids to feel locked into specific class make-ups rather than just bringing the people who were either best or else they most enjoyed playing with. So the changes they made to achieve this made every class a jack-of-all-trades to a certain extent. However, they didn't give every class and spec every ability or equalize their power in every role. They just ensured that every class and spec reached at least a minimum baseline in every healing role. This leaves enough difference between the class-specs to leverage for the sake of efficiency (and when I say "efficiency," I mean optimizing throughput for a healing team).
So how do we leverage this? To put it very simply, we identify where each class-spec's best use of mana lies and create a healing scheme whereby each healer is biasing their spell choice heavily in favor of that best use of mana. That is optimizing healing space.
This may sound like what healers should always be doing, but it's only possible in group play in which there is more than one healer. In a five-man environment, for example, where there is only one healer, you cannot specialize. You must cast all the spells necessary to keep everyone alive. This means some amount of direct healing as a druid, for example, even if direct healing is not your forté, because HoTs alone aren't going to keep a tank up through heavy damage. The economic theory of comparative advantage is useless if you are alone on a desert island, and optimizing healing space is worthless when you are a healing island in a five-man group.
No, it gets interesting when you are in a ten man or, especially, a twenty five man raid. The larger the group, the more healers. The more healers, the more specialization each healer can engage in, because a lot of niches can add up to a coherent whole. A single niche is just a niche.
Establishing The Foundation Of Healing Space
I primarily raid in ten man groups, so I'll primarily use that as the example. However, I'll note how this really flourishes in twenty five man groups at the end.
My raid group generally employs a healing team of a restoration druid, a holy paladin and a discipline priest (hey, that's me!). This has actually often been called the "holy trinity" of ten man raid healing teams and for good reason as we'll see from a healing space analysis. How do we leverage these three classes optimally?
The simplest approach for a healing team is what I like to call "see damage, heal damage." If someone is below full health, cast the appropriate spell (factoring in time urgency, amount of healing needed and mana efficiency required). This isn't particularly organized but it can actually work, especially if the healing team is extremely familiar with one another. The primary drawback here is that the disorganization can lead to sub-optimal healing: multiple healers addressing the same damage (leading either to overhealing or else a healer canceling their spell mid-cast, wasting some amount of time) and certain targets not receiving heals quickly enough.
One step up is straight healing assignments. Healer A will heal the main tank. Healer B will heal the off-tank. Healer C will heal all the non-tanks. This is much more structured. Overhealing will be reduced because, at least notionally, healers are not cross-healing the same targets. Every target has their dedicated healer and thus knows exactly what healing that target is receiving because it all comes from himself/herself. The primary drawback here is that overly strict adherence to assignments can leave healing potential on the table (Healer A being idle when the main tank is at full health while Healer C struggles with a burst of raid damage) and deviance from assignments leads to a greater and greater descent into the previous "see damage, heal damage" paradigm, with its own attendant drawbacks.
While the second option (assignments) is generally better regarded, each paradigm actually has its strengths. "See damage, heal damage" ensures that all the healers are capable of remaining active at all times (at least, all times in which there is damage to heal) which prevents useable healer casting time and mana regeneration from being wasted (a healer sitting at full mana is wasting all their itemization and talents that provide mana regeneration), while assignments provide the structure to keep healing from being wasted.
The ideal situation would be to marry the strengths of each paradigm into one, without also importing the attendant weaknesses. A healing space paradigm does just that. Let's look at how this works.
Crafting Healing Space
A restoration druid, as we noted, is best at keeping continuous healing "growing" on lots of targets at once, whether that's through Rejuvenation on multiple targets, Wild Growth or Efflorescence parked below a stack of raiders.
A discipline priest excels at preventing incoming damage.
A holy paladin is most powerful at pumping out strong direct heals on single targets (the value of which is amplified by their "reflection" mechanics, Beacon of Light and Protector of the Innocent...much as a battery of mirrors serve to focus and intensify a laser beam).
So we craft a healing space in which:
- The druid does keep her HoTs "growing" on as many targets as she can sustain and/or makes sense for the encounter but does not cast many single target heals.
- The holy paladin does cast her powerful single target spells on targets who are either particularly under siege or else are particularly low but does not concern herself with damage prevention (gears away from mastery) or heals over time (Holy Radiance, which has a mana opportunity cost).
- The discipline priest does cast her shields and mitigation spells often to slow the damage on targets likely to take damage in the near future, but does not spend much time or mana casting HoTs or direct healing spells.
A discipline priest is optimally using his mana when he casts a shield likely to be consumed by incoming damage. A restoration druid is optimally using his mana when he casts HoTs (whether single target or multi-target) that are likely not to go as overhealing. A holy paladin is optimally using his mana when he casts a powerful direct healing spell on a target at a low enough health that little of the direct heal goes as overhealing, and the target of the heal reflection also is low enough health that little of the reflected heal goes as overhealing.
The result is that, as long as there is damage to be healed, you have healers who can be active and engaged, yet there is implicit structure that minimizes the overhealing that chaos can cause. The druid is a champion of overall healing, but all that creeping healing is useless if targets die before they can tick back up to a safe level. That's where holy paladin direct heals come in, swiftly (relative to druid HoTs) pushing a dangerously low target back to a safer level where the slow healing over time can finish the job passively. But the paladin's big heal is useless if the target dies before the heal lands (or before the paladin can find time to cast on that particular target). That's where discipline shields come in, providing an instant buffer on targets in critical condition, keeping them afloat until the healing of the paladin and druid can save them.
At a more abstract level, the discipline priest provides a preventative umbrella over everyone, underneath which the druid's garden of HoTs provide a "healing aura" constantly moving everyone upward and the holy paladin combats spikes downward in health to anyone with spikes upward in health through spells.
In Conclusion, More Explanation
In this healing space, each healer has a clear-cut role, which allows them to fluidly move between the same targets, but in their own space. Think of it as a separate dimension...each healer is their own island, in their own dimension. You, as a healer, are responsible for everyone...but only within that dimension. As long as every healer optimizes the throughput of the spells that make up their dimension, the healing team is optimizing their overall throughput.
Except when necessary, you need to resist moving into a fellow healer's dimension. Each time you do so, you detract from the efficiency gains. Your healing team has only so many GCD's (global cooldowns) and mana to work with over a given encounter length. Using your GCD and mana to address a small bit of damage on a target, when a druid's HoTs can address it, may seem harmless enough, but it's a GCD and mana you could have used casting a Power Word: Shield. On a one-off basis, it doesn't matter much...but these little decisions add up over the course of the encounter and undermine the benefits of specializing within the crafted healing space.
For the sake of brevity (this post is barely more than a haiku in length and I like that succinctness), I won't go through a similar healing space crafting for every combination of healing classes. But you can see the format: identify what a healer does that is an optimal throughput use of their time and mana and give them that specialization across the entire raid and task them to use non-optimal spells as little as possible. A shaman, while not included in my example healing space, can easily be crafted a space based on their unique power on low health targets. All that's necessary to create these types of healing spaces is multiple healers. There can even be duplicate class-specs as long as each of the duplicates can, through talents, gearing or playstyle, provide a different specialization (two holy priests can each specialize differently based on different chakra states, two discipline priests can provide absorption and direct heals, etc).
The key is for each healer to decide, for an encounter, what they will be spending their mana on, working to make that efficient (through itemization and talents) and then sticking to it as much as possible. If you've geared and talented for making your direct heals as powerful as possible and then bias your spell choice heavily to direct heals, you can achieve a lot more than spreading your gearing and talents out and trying to do lots of different things...as long as other healers are picking up the other forms of healing.
As I mentioned previously, this can be taken to an even greater extent in twenty five man raids, where instead of two or three healers, you're working with five or six healers. Since every healer is still responsible for everyone, you handle more healers by breaking healing space into even more granular roles. How about a holy paladin who specializes in stacking mastery for absorption and focuses on overhealing targets to build up larger and larger bubbles on targets she expects to take big damage soon? That's happened in some world-ranked raid groups. How about a discipline priest who stacks crit and haste in order to pump out Prayers of Healing to coat the raid in Divine Aegis bubbles (since Power Word: Shields can't have constant uptime due to Weakened Soul)? These are the types of niche roles that ten man raid healers simply can't afford to try because it's too small a niche for the roughly 33-50% of the total healing you're responsible for. The more healers, the more specialized you can afford to be and the more specialized your healers must be to fully leverage each healer.
I'm Done, Thanks For Reading
We are here to protect you from the terrible secret of (healing) space.