Curse of Strahd
A haunted mansion inhabited by the undead spirits of the knights who once belonged to a group known as the Order of the Silver Dragon. The Order was dedicated to the service of Argynvost, a powerful silver dragon, who challenged Strahd. Strahd killed Argynvost and kept the skull. The knights have since been doomed as revenants, eternally seeking revenge that is beyond their grasp.