How to beat Dancer of the Boreal Valley in Dark Souls III

She's danced her last, now!

All Dark Souls III boss and quest guides come with a giant spoiler warning!

The Dancer of the Boreal Valley is a graceful, lithe foe - and a tough opponent. Also, she really reminded me of a messed-up version of Pearl from Steven Universe. Am I the only one? No matter - follow her deadly dance moves to find a way to put this flapper out of commission for good.