Here's my method. I play sign heavy and for whatever reason didn't have the proper bomb diagrams.
1) Hit Quen and keep it up whenever it blows out.
2) Lay Yrden traps
3) Hit her like 3-4 times and dodge or until she hits and kills the Quen
4) Run away from the 3 health suckers when they spawn
While Yrden keeps her corporeal (as Geralt hints by saying something about keeping her bound to one place), Quen keeps you from getting gutted, and the health sucking wraiths disappear after only a few seconds... rendering them completely worthless to her if you run a few feet away. If you stick around to attack them, they have time to regenerate her health. Enabling "sustained glyphs" helped. I didn't need to use any materials doing it this way.
EDIT since I can't comment on others' yet...
Reading other people's methods makes it clear to me how variable this game is and just how differently a single fight can be approached. My Quen/Yrden approach probably only worked well for me due to the fact that I have both fully developed with 2 mutagens and additional bonuses on my gear boosting the intensity well over the 30% mark. I only needed to use each about 4 times for the whole fight. Most monsters can hit me 2-3 times before a single charge blows out, and I can lay multiple traps that last minutes, so she never gave me damage.