Magic mirror

the mirror has runes and jewels and was created by an ancient wizard in an ancient kingdom for a king who wanted to be able to move among his people without them knowing so he can know what he needs to work on after doing this for years as a man he decides to test the limits of the mirror's powers and imagines a young woman and feels himself transforming into her

this is what he looks like

to continue being among his people after years of doing this and his kingdom was prosperous and profitable he hands off ruling the kingdom to his son and daughter in law

as time goes by the king passes away in his sleep a few months after his wife or so they thought unknown to his son the king and his daughter in law swapped bodies and it was her who died as him shortly thereafter the mirror vanished and along with it any trace of the kingdom even from history except legends but there is a story saying the mirror would reappear?