The Necromancer robe bottom can be reverted at any time by choosing the right-click option "Remove-kit Necromancer robe bottom", which will return a Necromancer kit and a Dagon'hai robe bottom. However, the 10 Fine cloth used to make this item will be lost. When using the necromancer kit on the Dagon'hai robe bottoms, the chatbox will say they've "taken on a more sinister look".