So a few inconsistencies..
One, the magician would have to inscribe the mark upon her neck, how would he have done that without her knowing or meeting him?
Two, the majority of the people involved in her story were at her execution. Wouldn’t the second individual have had to be there in the tower with the magician to cast the spell?
Three, if the magician loses his memories...how would he even know the spell was cast unless he was told?