Sanctum

Sanctum is the fifth floor in the facility, characterized by its runes and brick makeup. It is mostly inhabited by Constructs and Machines, with some mages. There are very few undead, though some are spawned by Soul harvesters and Ghost lamps. Its Challenger is the Myriad. Unlike other floors, you are able to end a run after defeating the boss, or you can go deeper if you have obtained all four Seals