The Mantra Reactor appears as a handheld metal energy core with eight points. Underneath it lies eight colored spheres, each representing a Mantra Affinity, which are used to combine the Mantra into a singular energy form.
After the Seven Deities initiated their plan for the Great Rebirth, they began collecting the souls of humans to convert into Mantra. That Mantra would be stored inside the Mantra Reactor to contain and utilize the souls for the purposes of the Seven Deities. The Mantra Reactor was stored within the core of the Karma Fortress to use against the Gohma and was used by the the Seven Deities as their grand weapon against their enemies. However, due to Asura's interference, Wyzen's carelessness and Olga's foolishness, the Mantra Reactor was drained of much of its power and would take another few centuries to regain the amount of power lost. By then its power had been regained, and all of the souls had been drained by the Gohma as a result of Deus's defeat by Asura and Yasha.
After Asura was rendered comatose from his fight with Chakravartin and the Karma Fortress was reduced to rubble, Yasha scavenged the Mantra Reactor and placed it in Asura's body as a vessel of power for the remainder of the story.
- According to Yasha, the Mantra Reactor held seven trillion souls worth of Mantra before it was permanently drained by the Gohma.