Karmelita will be the death of me

She has to be the hardest boss so far. It could be a case of getting good. But it’s a serious struggle and hardly feel like much progress is being made.

I’ve mostly stuck to either Reaper or Wanderer crests when fighting. And the waves before her aren’t too much of a hassle.

But she is so painful and stupidly fast as the fight progresses.

Is there any good strategies for this? I’ll try anything before I maybe take a long needed break.