She doesn't have very good offensive magic, but if its all concentrated on one guy...
My latest misadventure: Yxunomei
Toughie. I used the 5th level ranger spell summon animals II to get 4 cave bears. Once bless, protection from evil, draw upon holy might and defensive unity were up, I charged in. My guy immediately stepped on a trap and got confusion and poison
but my faithful cave bears "beared" the burden of taking hits until I recovered. Course, by that time my bears were dead and all I had to show for it was 3 downed yuan-ti, but I made it out with still around 80 hp left. I held at the door, wacking away at Y. However, the half-strength group of yuan-ti and summoned skeletons started harassing me, so I retreated to the histachii room. The winding walkways made a great chokepoint, and I was able to isolate Y and bash her head in.