In the video game series, the medallion starts as a helpful piece of equipment for the player, alerting them when there are either monsters or magic nearby. This helps the player know when there is danger nearby, or if they have it tuned to look for magic, when they are near a place of power.

This worked with most of the magical beings in the game, except for dopplers and higher vampires, who couldn't be detected by the medallion. 

The medallion was only significant in the first and second games, though, as those powers were later adapted by the character in the third installment in the video game series. Instead, the medallion would vibrate at infrequent intervals, sometimes indicating danger or to give the player a clue.