It's a common thing to say that Preservation is a 'combo' healer and to see a lot of different spell sequences listed on guides and videos. While it's true that the way Preservation works means you are supposed to use spells in certain specific orders, the combos themselves don't actually matter. The important part is the reasons we came up with these combos in the first place.
There are several talents, buffs and interactions that lead to the combos. Once you know all of these interactions then you will naturally be able to come up with the combos on your own and modify them to suit your specific needs. Understanding the basics of the spec gives you flexibilty as opposed to memorizing strict cast sequences.
There are four things that dictate the order of the spells you cast, these are:
- Echoes
- Buffs
- Profile
- Time
For the echoes, the important thing to remember is just that echoes are consumed by the next healing spell after appling them. You are supposed to use your echoes and ta to amplify another healing ability by using them right before said ability.
For the buffs, there are some buffs that you need to active before using certain spells, most of them tied to ve. The main example of this is coy: You always want to use ve before db because ve activates coy which in turn heavily buffs db.
If we combine these two things we end up with one of the most common Preservation combos:
Using ve before ta means we activate coy but still have the echoes from reso ready to amplify our db.
Now for the healing profile, amplifying db is good to heal damage over time, but won't be very good when you need burst healing. For that you would ideally use sb or lb. To do healing with lb we first need to apply echoes, then use ve and finally heal ourselves for a high amount very quickly, mainly with sb.
And this leads to another of the common Preservation combos, which is:
And so, by knowing what echo does and how ve interacts with both sb and db via coy and lb you can come up with these combos on your own, without having to memorize the sequences.
Then, the final factor is time. Every spell works over a certain amount of time and this affects how you combine them. lb has a five second duration and so you need to do healing on yourself very quickly to take advantage of it, on the other hand coy lasts up to 20 seconds, which means you don't need to use ve inmediately before db and instead can space it out. This results in you being able to combine the two previous combos:
Due to the duration of coy, you can easily use the ve from a previous burst healing sequence to fuel your next db. But do note that this is only optimal if you need to heal damage over time closely following burst damage, if you don't need the healing from db yet, its fine to let coy expire and then apply it again after when it makes sense to do so.
And then, because lb only lasts for five seconds, and db heals over a longer amount of time (upwards of 20 seconds) with a very small amount upfront, it doesn't make sense to use db right after consuming several echoes with ve.
In the case of wanting to amplify db, you would apply the echoes after using ve, and if you want to consume echoes with ve for burst healing you would instead follow that up with sb or lf to transfer that via the lb.
And then for stasis there is no stasis combos, you simply want to fill your stasis with your strongest spells. The strongest spells are db, sb and ta. The specific order you store them in can vary depending on what you want to accomplish following the same rules as before.
In the case of wanting to do over time healing, you would put ta before the db
And if you want to instead do burst healing, you would put ta before sb
Wether you put the final spell at the start or at the end of the stasis doesn't really matter, the only important part is using ta before the spell you want to amplify. The same way you would do when using the spells outside of stasis.
In the case of wanting to use your reso echoes for a different thing that isn't sb or db, you would instead put the ta at the end. This way when you release your stasis your last cast would be the ta, giving you five free echoes on the group. The main use of this is to release a stasis followed up by casting another ta to have upwards of 10 echoes on the raid before consuming them with something like ve followed by ec.
Another thing worth mentioning that isn't clear from seeing the combos is that you don't need to use all of the spells of the sequence. If you need to quickly heal up your group and plan to echo ve and then lb a sb for that, but after casting the ve you notice that the group is already at full health then you can cut the combo short there and not waste the sb.
The sequence might be the most ideal order of the spells, but if you already accomplished your goal of healing the group then there is no need to go all the way and do more overhealing just because certain guide tells you to.
And so, once again, the combos themselves don't matter. The important part is how your spells interact with each other and thinking of the best way to achieve a specific healing profile using those interactions. By having a better understanding of the spec you will be able to easily come up with the combos on your own on a moment to moment basis and won't need to memorize a bunch of specific sequences.