A Fatal Vulnerability Dünste informs Denken's and Frieren's parties that Edel has retreated from the dungeon and that mind control is not an option against the replicas. Lawine and Kanne arrive at the scene and tell the parties that the monster they are facing is a Spiegel and that the replicas it creates have no unique weaknesses. Everyone present concludes that Frieren's replica must be defeated before they can destroy the Spiegel. Before heading into battle, Fern discloses Frieren's fatal weakness: she cannot detect mana when she casts a spell, a vulnerability typically found in beginner mages...