Thought she was an absolute cakewalk on my first playthrough... figured it would be the same for NG+ but holy*****, she seems to be on another level the second time around. Never looked up the cheese method or I would have done it, but the key for me was playing super defensively, grappling constantly during the illusions (or using a snap seed), and then using a combo of mist raven and mortal draw to deal some vitality damage during phase 3. The important thing is staying defensive, even when her posture is close to breaking. I had so many attempts where I would just get a little carried away trying to push her over the edge, only to have her kill me every time. Counting can seriously help too - 5 counts on the windmill attack and then she rests - that kind of thing.