I've been trying to get this chest piece for my warrior and have always used the "remove illusion to get through doors" trick and I've recently found that my gnome-box, can't do this trick in Chardok. I could get into the Prince room and the locked door that leads down to the Overlord with my OGRE warrior, but my GNOME couldnt. I tried Spectre/skleteon/frost goblin, illusions and no luck.
Also, tried the camp out against the door, log back in method and no luck there either.