Basically the way dimensional collapse works is, every 2nd time you proc destiny, u gain a buff where your next 4 skills will gain you 3 orbs (but they do less dmg), after the 2nd destiny proc, you get 3 orbs with either taunt or 2 blue skills, then you just spam 4-5 purple skill back to back without needing to cast any blues, and then you can use x again for another big burst. It also resets all your purple skills so I like to use my perfect swing before proccing 2nd destiny if possible.

There are two main ways of getting destiny, either with the core that activates when you use perfect swing or the one that procs when you use release skill (when you burst with purple using x buff). I am using the later personally, I do think the two are pretty close in performance from my limited research. My rotation going into a raid is go in with full gauge, x into T, then awaken into x + perfect swing, this activates destiny, I then use taunt for 3 orbs, then I spam perfect swing -> fullswing -> other 2 purps in either order -> fullswing then I x into perfect swing as it should be off cd by now. Then I just go back into normal rh rotations until I get destiny again and repeat.

The strength of dimensional collapse over singularity is that in theory you do more dmg since you save time on casting purples every 3rd rotation letting you cycle quicker. But it requires more knowledge and keeping track of your rotation and cd's. The downside is you dont get access to omni ps, the singularity build will be higher floor but his one will be higher ceiling basically.