Chapter 51

At the hall's mouth, Frieren and Denken weigh how to destroy her flawless double, reasoning that a perfect copy should share the frailties of any living mage. Richter suggests overpowering a stronger opponent with restraint or hypnosis, but Frieren proves immune to both when Methode tests them on her; the hypnosis cannot pierce her dense, if old-fashioned, mental defenses. Methode guesses that Edel, a second-class mage with almost no fighting skill, might crack them, yet cautions that hypnosis only bites on a target with an intact mind, something the clone may not possess.

Edel, meanwhile, cowers behind a pillar with Dünste and Blei as Sense's duplicate patrols nearby. She judges the copy as fearsome as Sense herself, its hair woven with layered spells and a near-limitless capacity to improvise, since manipulating natural elements has grown more efficient than conjuring matter outright. When the clone slices the pillars apart, the trio raises a spherical shield, but the double breaks it by both crushing mass and slipping technique through at once. Edel makes eye contact and commands it to kneel, only to be run through, confirming that the copy has no mind and merely mimics its source.

Beaten, Edel urges the others to flee and find someone able to fight it, then smashes her bottle to escape, the emerging golem shielding her from a final strike. Back at the circular hall, Frieren concludes they have too little to go on and must prepare for a mindless clone that can only be broken by force. When Denken asks whether she is capable of that, she is unsure, and Fern quietly offers that, if it comes to it, she may have to kill Frieren's double herself. Frieren smiles and turns the group toward planning a strategy.

The mages at the circular hall find Frieren resistant to both restraint and hypnosis, narrowing their options against her clone. Edel, Dünste, and Blei lose their stand against Sense's duplicate, with Edel forfeiting after being impaled and proving the copies are mindless. Fern volunteers to kill Frieren's clone should brute force become necessary.

Dungeon Battle, or Danjon sentō, was released on May 26, 2021 over eighteen pages of volume six. It continues the second stage of the First-Class Mage Exam Arc and adapts into the anime's twenty-fourth episode. The chapter establishes that modern offensive magic, built around manipulating natural elements, is poorly suited to combat inside dungeons.