A Green Stone is a magical stone.
King Charioce XVII, in his rebellion against the gods, raided many god-worshiping temples and stole numerous artifacts including several magical green stones.
These green stones possessed the ability to drain one's life force in exchange for giving one power that triumphs the gods and demons. In his war against the gods, Charioce XVII formed the Onyx Task Force whose members were to implant a green stone into their chest. Doing so would eventually kill the Onyx Task Force members, but it would also enable Charioce XVII to annihilate the gods and enslave the demons.
The Onyx Knights willingly gave up their life to join the Task Force. Charioce XVII himself kept a green stone on his person and whenever he used the ancient weapon Dromos, the Onyx Knights would share the burden of paying the toll for using Dromos.
Because the green stones empowered the Onyx Knights against gods and demons, they granted no resistance against humans. This enabled the half-bloods such as El and Nina Drango to use their powers against the Onyx Knights because of their human blood. El could drain the energy from the green stones while Nina could easily defeat the Onyx Knights while transformed. Regular humans also possessed an advantage against green stones-empowered Onyx Knights.
Following Bahamut's defeat by Charioce XVII, the green stones presumably ran out and the enslaved demons were kept in the capital by giving them a salary. The Onyx Knights had also died out and were no longer needed.
|Objects||Alessand's dagger • Amira's compass • Amira's pendant • Bahamut's Talon • Barossa's dagger • Black Bible • Bounty Hunter's Bracer • Charioce XVII's bracelet • Demon Key • Dromos • El's ocarina • El's toy • Favaro's crossbow • God Key • Golem • Green Stone • Hoverboard • Maltet • Marginal Golem • Martinet's concoction • Nina's whip • Précieuse • Rita's antidotes • Rita's staff • Smoke Bomb • Transcendence Key|