Priority based. I think the Ninja walk in shadow thread has the priorities somewhere. If I made a rotation it'd be a lot to type out. Honestly I suggest looking at the priorities then practicing on a dummy to get a feel for it. There's going to be a lot of if X is the situation than use Y attack. If X is close to CD skip Y attack and use Z. It takes a bit of practice. If you can't find the priority list ill try to type the stuff out for you or give you a loose rotation.