Did her as a 27th rogue easily.  She walks in a little loop stopping 3 places for about 5-10 seconds at each one.  While keeping out of her aggro range kill the one other snake lady with her.  Then you can easily take her down.  Use kick to keep her from spell casting, her melee is weak. I used a potion of Nature Protection, end had half health at the end each time I killed her.