How the Rhodic Empire controls their magi

The only way you are allowed to openly practice thaumaturgy within the Rhodic Empire, is to be registered with the Church of the Golden Conquest. Part of the process requires the removal of the registering practitioner's pinky finger. The finger is preserved and held securely within the province's designated church vault. If the mage were to ever go rogue or refuse to work with the church or the empire, they would be branded a heretic and hunted down. The finger is attached to a specially enchanted amulet that revives the finger and allows the wearer to use it to inflict its owner with curses and use it to track them down.