How to make a mirror in the editor??

[Tiger]

Have different models that show stages of change. One where you look like normal, one that shows you as a monster and all the stages between that. Place all those models in the same place, where you want them and make all of them inactive except the one where you are normal. Then you can make them change with triggers or timers. Like the others said, you could take a screenshot of the surroundings so that the "mirror" shows what's behind you.