Sealing magic involved the spellcaster neutralizing an opponent's magical ability or entrapping an entity within an object or confined space. In the case of a demon being sealed while possessing a person, the demon would gradually lose power until being forced to relinquish its possession and return to its true body where it's sealed. Via a paper seal, a magical entity could be imprisoned within an object and made unable to maneuver outside the sealed area. The seal could be easily undone by removing the paper. Inscription runes could also be used to seal certain magical abilities over a specific area.
- In Gloom of Held, Elluka Clockworker mentions using a "capture spell" to restrain Platonic; it is unknown if this spell is related to sealing magic.