Located somewhere in the floating island Cube, Hell's Core is used as a laboratory where Demons are born, as was the case of Minerva Orland, and also reborn, as was the case with Tempester and Jackal. According to Lamy, this is because of a contract made with the Underworld King, making Tartaros an immortal Guild. The entire mechanism seems to be controlled by a Demon with tentacle-like extensions as these creatures were taken over by Mirajane Strauss, who then proceeded to use these in order to destroy Hell's Core.
- ↑ 1.0 1.1 Fairy Tail Manga: Chapter 380, Page 7
- ↑ Fairy Tail Manga: Chapter 370, Pages 9-12
- ↑ Fairy Tail Manga: Chapter 380, Pages 8-12