If the alt key does not help (the mutant should drop the crystal and a unique saber), this problem is fixable by temporarily swapping a file from a working save. You are the second person to run into this, that I know of, so I'll post instructions before you get back (if I remember).
Did you try reverting to a slightly older save, if available (such as just before being summoned)?
You could try deleting the files in the dynamic folders, then reloading a previous save, though that was not the problem in the other save I looked at.
dynamic folders;
'..\Beyond Divinity\Acts\Act1\Dynamic', '..\Beyond Divinity\Acts\Act2\Dynamic', etc.
These folders are used as a cache for the game. Files are created / copied there from the save game folder when you load, and written / copied to those folders when you save a game. The files will be re-created as required the next time you start Beyond Divinity. If there was a corrupt file in those folders, deleting the files should fix the problem.
