Rehash/Resign the save, load and play. Work your way through the temple killing the Hollow men as you go. Get to the chest and open it to get the lever and return to the guy your working for and the achievement will unlock. Created by: H4NNiiB4L Enjoy: http://www.xpgamesaves.com/files/file/1160-fable-3-the-dark-sanctum/
Hope you find it easy, it could have been saved a bit later then it is but hey what's a little work for an achievement now and then lol