How to morally destroy the Pale Lady

The spell Ghost Walk is part of the Apocalypse Spells mod I think. I really suggest this mod as it adds alot of useful and very fun to use spells that will add tons of gameplay strategies to the game. Here I found very difficult to kill the Pale Lady at the level I was at that time (14), so I decided to apply some strategy and, so, to put this spell to good use.