The Overseer Musical Chair is a new, alternative application of the Ancient Music. While the music boxes are meant to be used as deterrent against supernatural powers and individuals, the musical chairs are torturing and interrogative devices. They look like reclining chairs, but with leather restraints and dome-shaped diaphragms, set around victim's head. The music causes extreme pain to the victims, as evident by the screams and whimpers during an interrogation recorded by Álvaro Cardoza. In fact, Overseers are advised to gag the victims to stop them from screaming and begging. It is unclear when the device was invented but in 1853, two were used to torture the captured witches in The Royal Conservatory. The witches were driven mad and killed by the repeated "healing sessions" and only one survived by the time Billie Lurk arrived.
The Abbey of the Everyman seems to believe that the physiology of heretics was changed and corrupted, part of their body turned into what Cardoza called "heretical organs", and it is due to these organs rejecting the music that causes the pain. They also believe that the music is the only cure for such condition, but those who are too corrupted, will be killed instead. Cardoza, however, couldn't find any evidence of corruption during an autopsy of a witch. He concluded that her body had been successfully healed but death is the price for such treatment.
- The Álvaro and the Abbey contract requires Billie to put Álvaro Cardoza on a musical chair, and let the contract giver deal with him personally. It it not known whether he is affected by the device.