Labyrinthos (ラビリントス Rabirintosu ) was the Unrestricted Spell used by "Great Embracing Furnace" Molech, the Chancellor of Töten Glocke's Nine Eternal Divine Scales. It was capable of controlling space on a large scale.
With Labyrinthos, Molech transformed his body into a large labyrinth resembling a gigantic ox, which engulfed both enemies and allies along with the space around them. The size of the labyrinth was somewhat flexible, and was deployed with a larger size than usual during the final battle of the Great War of the Middle Ages, covering both Brocken Fortress and Tendōkyū. When Labyrinthos was to be activated, the ox skeleton which made up Molech's body began to turn into yellow sparks and disintegrate bone by bone, spreading out over the space which was to become the labyrinth. Finally, an Unrestricted Spell Insignia started up, activating the Unrestricted Spell. This meant that the activation of Labyrinthos took some time to accomplish. As the Unrestricted Spell used Molech's own skeletal body as material, destroying the labyrinth would directly result in Molech's destruction.
After Labyrinthos had activated, the space within the range of its effects cracked, shifted, and was mixed together, capturing Molech's targets inside the labyrinth within a few seconds. Within the labyrinth spread a dim maze made of stone, its passages wide and its ceiling high to accommodate the builds of Crimson Denizens. There were no traps or tricks in the interior of Labyrinthos and it looked like a normal building at first glance. However, the interior was more complex than it appeared, with the space inside strangely distorted. As it was effectively the interior of Molech's body, his presence filled the surroundings, making it difficult to sense other presences. On top of that, the connection of space within the labyrinth could be freely controlled by Molech's will, meaning he could construct a battlefield that was disadvantageous to enemies and advantageous to allies. However, Molech himself could not grasp the fine details of the labyrinth interior beyond people's presences and existences.
The labyrinth was constructed from surrounding material gathered into the space being controlled. Since Labyrinthos had no ability to strengthen this material, there was no great difference in its strength when compared to an ordinary building. By using the ruins of the destroyed labyrinth or bringing in surrounding material, the labyrinth could be reconstructed. Labyrinthos could be rebuilt as long as Molech had power. This reconstruction was of a nature which could possibly be obstructed by an Unrestricted Spell Master.
Escaping the labyrinth was extremely difficult because of the controlled space and the labyrinth's reconstruction, and if Molech had his own troops housed inside, Labyrinthos could easily hold out against 100 average Flame Haze. When deployed during the Great War of the Middle Ages, Brocken Fortress guards were confined inside to intercept intruders.
Though Labyrinthos was rarely used, it had never been defeated. Due to this, Molech had once jokingly said, "you could say that it's impregnable". Chernobog thought of this statement as the one time Molech had displayed pride and believed it completely. In reality, though it had never been defeated, it was by no means impregnable and was simply "very hard to destroy". Molech himself was aware that it was something that would be defeated by a powerful enemy whose power exceeded his.
During the final battle of the Great War of the Middle Ages, Labyrinthos was used to buy time until the completion of the Grand Scheme, deployed over a vast range to trap the Flame Haze "Flame-Haired Burning-Eyed Hunter" Mathilde Saint-Omer and Manipulator of Objects" Wilhelmina Carmel and force them into a war of attrition. Molech succeeded in engulfing the two, but Labyrinthos and thus he himself were destroyed by the combined work of the two Flame Haze, in which Wilhelmina laid out her ribbons throughout the labyrinth and Mathilde used them as markers to use her full power in sending her Knights throughout the labyrinth to blow it all up at once.
- This spell, its name, how it was thwarted, and its user's appearance may have been inspired by the story of the Labyrinth from Greek mythology. The hero Theseus fought the Minotaur, a half-bull creature, within the labyrinth, and used a ball of thread to find his way out.