On Branding Heretics is a book found in Dishonored.
The Heretic Brand is reserved for those Overseers who have committed heinous acts against the order, but have not broken codes that would otherwise result in execution. No contact, aid or shelter can be given to one bearing the brand; that person is forevermore unwelcome to the Abbey and its affiliates.
When used, the brand is applied to the forehead, so all can see the sins of the recipient. The chemical compound acts immediately, scarring the heretic for the remainder of life.
The Interrogation Room here at the Office of the High Overseer stands ready for branding ritual, should the need arise. The recipient must be strapped into the interrogation chair and restrained as the brand is applied. The Heretic Brand itself is to be stored in the same room.