Does anyone know name of any movies with these descriptions?

A queen has one condition to marry is someone be able to win a dual against her, if someone could win a fight with her she would marry her and give her the kingdom.

A king finds a strong person and exchanges body using witchcraft and so that the strong person could win the duel using the body of the King and he wins the duel and she marries him.
But later she finds out he is not really the one that won the fight.

Movie 2:
A group of people produce horror short films but they have a real killer (serrial killer?) among them that kills them one by one when they are creating a short film.

The second sounds a bit like Behind The Mask: The rise of Leslie Vernon.

first one: ring of the nibelungs?