Jade Sphere
The Jade Sphere is the profession mechanic of the catalyst. Hitting enemies generates energy, and you spend this energy to summon a sphere that deals minor damage and provides yourself and nearby allies with boons, most notably permanent thanks to and . Each attunement has its own sphere, and their cooldowns are not shared. Thanks to the trait , you can generate Energy even while a sphere is deployed.
You also gain improved attributes from Elemental Empowerment effect from traits like .
Damage
The playstyle is easy to explain, but not so much to execute. You want to rotate through all four attunements while using their Sphere and their spear Etching skills. If you are spending more than 5 seconds on an attunement, you are too slow. Cast (preferably inside the fire Sphere) and (on Air or Fire) off cooldown for damage.
In long fights, if you do not have from another player, your spear Etchings will not be ready once you attune to an element for a second time. When that happens, you have to skip the Etching, cast whatever weapon skills are off cooldown, and move to the next attunement to cast its Sphere off cooldown in order to maintain permanent Quickness. Note that you want to always cast the fire etching, , right after to increase its damage.
If not using spear, the idea is the same: rotate through all four attunements off cooldown to use their Sphere while casting all your damaging weapon skills.
Elemental Empowerment
As a catalyst, you gain stacks of Elemental Empowerment which increase all your attributes. This obviously increases your damage and survivability a little bit, but they are also important to increase boon duration.
provides 3 stacks of Elemental Empowerment. To get more, you need to inflict crowd control due to . Pretty much all your cc skills on any weapon are also damage skills and thus part of your normal rotation, so you don't need to worry about this trait. will also give you an aura periodically, and every time you get an aura you get one stack of Elemental Empowerment, such as when you attune to due to .
Quickness
You provide quickness with the traits + . You want to swap attunements off cooldown and use their Sphere immediately. This also provides other boons, namely permanent and some .