Best Deck/Cards for DS & Lumi

20% from level 100 ambition

I thought it was only 10%, I can't see it now in the UI since it is cut off, but a quick search tells me 10%.

I'm pretty sure the rank-based set effects stack? You know, the "three B/A/S/SS rank" effects. At least, they did when the system first came out. I admit I haven't checked after this update.

Those effects stack, the class-specific ones do not.