I sealed her in a prison of glass. It is the only element that can withstand her evil.
She stalked these lands as a human once, killing the man who thought he was her father and vilifying her step-family.
So if you are wandering the forests of Western Europe, and should happen upon a glass slipper – do not touch it. Do not listen to any voices that may come from within it.
Treat it with the utmost fear, for it holds the demon known as Cinderella.