Gameplay
Preservation is a somewhat complicated healer. It's heavily based around the usage of several short-cooldowns and the empowered spells, it lacks a real useful spammable healing button, has a shorter range than any other class and it weirdly goes from having a lot of mobility tools to also being constantly immobile casting long channels.
Using just the right amount of resources to respond to any given situation without overcommiting cooldowns that you will need soon is a key aspect of succeeding as a preservation evoker.
Echo
This is the key component of the spec. When you cast Echo on someone, the next healing spell you use on any target will be replicated on that person, consuming the Echo. Covering your group with Echo and then casting a spell is how the spec uses it's resource to increase it's healing and to cover more targets than what the spells are normally capable of. Good Echo management is key to playing preservation well.
For a detailed list on all the ways Echo interacts with the rest of our spells you can check the interactions page on Echo
Empowered Spells
Preservation has two empowered spells: Dream Breath and Fire Breath
Dream Breath is a frontal cone aoe with both an upfront heal and a heal-over-time. The higher you empower it the more healing the initial hit does in exchange a shorter over-time heal. This is your healing empower spell and the centerpiece of most of your kit. When Echoed, it will do it's upfront healing and apply a second version of its heal over time on any target that had an Echo.
The second empower, Fire Breath, is a damage spell and it works in the same way as Dream Breath. Fire Breath is still an important part of our healing kit because of Life-Givers Flame and Leaping Flames. Being a damage spell, Fire Breath can't be Echoed.
Casting Fire Breath will give you the Leaping Flames buff, which makes your next Living Flame cast one extra flame per level you empowered the Fire Breath. These extra Living Flames can proc their own Essence Bursts and will be aimed at enemies if your Living Flame target was an enemy or at allies if you used it to heal. If you cast Living Flame on an enemy with Leaping Flames up but theres not enough hostile units close enough to target with the Living Flames any extras will heal nearby allies instead.
The other part is Life-Givers Flame, which excels in aoe scenarios. On mythic+ unleashing a max rank Fire Breath on at least five hostile targets it's enough to heal your whole party back up, making it just as good as our dedicated healing spells at healing your group.
Merithra's Blessing
Our apex talent Merithra's Blessing has a chance to activate when you spend essence and also does so every time you use Dream Breath. It replaces your Reversion spell with a powered-up version that has a stronger initial wave of healing that then bounces around to different nearby injured targets. Merithra's Blessing interacts very well with Echo, as the spell is replicated completely and will do all of its bounces for every Echo that you consume with it.
Using Merithra's Blessing also carries with it all the normal effects of a Reversion, which include Golden Hour and applying the heal over time effect that applies Grace Period
Temporal Anomaly
Another fundamental part of the preservation toolkit is Temporal Anomaly. This is the tool that lets you quickly cover people with Echoes. Notably these Echoes are weaker than ones applied by manually casting the Echo spell: they replicate spells at 30% effectiveness baseline and 45% with Timelord, as opposed to casted Echoes which do 70% baseline and 105% with Timelord.
The tradeoff here is that Temporal Anomaly lets you apply Echo in a very quick and efficient way, not using essence at all, but in turn do less healing. In raids you will combine the two types of Echo to cover as many people as possible before you use healing spells, while in mythic+ you might choose between one or the other depending on a lot of factors like how much time you have before needing to heal, how much available essence you have, or what spell you are casting to consume them.
All the interactions that work on Echo do the same thing to Echoes applied by Resonating Sphere, they simply do smaller numbers. The one exception to this is Grace Period which will always increase healing taken by 10%.
Reversion
Reversion is a spell that on its own is just a heal over time that gets extended on critical hits. The complexity of this button comes from all the extra effects it gets added to it via talents, like Golden Hour, Lifespark and Grace Period, on top of the resource generation it provides by having a chance to give us Essence Burst on application.
While you might not find yourself Echoing the base version of Reversion a lot, you gain all of its benefits when you use Merithra's Blessing which means all the effects that increase its power are very valuable anyway. Reversion is also our best spot-healing tool as Golden Hour scales very well with high damage taken in a short period of time.
For more information on how Reversion interacts with the rest of our kit you can read the interactions page on Reversion
Emerald Blossom
Emerald Blossom is a very unique spell that serves as our alternative to Echo for using essence. To note Emerald Blossom usually costs a fair bit of mana, but the effect of Essence Burst not only makes spell cost no essence but also removes the mana cost, making blossoms much easier to fit into your gameplay.
Due to Twin Echoes, Emerald Blossom represents a key part of our gameplay as you constantly weave between your essence consumption tools to maximize the value you get. Using your Essence Bursts in Emerald Blossom will do a good amount of healing and also give you a stack of Twin Echoes, which you can then use with your natural essence (as Echo is very cheap mana wise) to apply just as many Echoes as you would have if you consumed the Essence Burst with it.
Emerald Blossom also comes with a whole set of interactions and talent support like Fluttering Seedlings, Field of Dreams, and Flameshaper's Consume Flame.