Magic Slayers Guild

History
During the preparation for war with Ishgar, God Serena had began his own guild; hidden within the mountains in Bosco. This guild was designed to be the strongest in the entirety of Earth Land; made up entirely of wizards who exclusively used different forms of Slayer magic. When the war finally begun, God Serena hid his guild from the outside world using a series of incantations, before finally joining his fellow Spriggan 12 members for war.

During the final moments of the Alvarez invasion, Gildarts Clive and God Serena were locked in combat, until finally Gildarts defeated God Serena. Unbeknown to all, just before Gildarts' final attack landed, God Serena uttered a single incantation "Life-Force Dragon's Holy Revival" (Inochiryokuryu no Seinaru Fukkatsu), a Dragon Slayer spell that would allow his body to immediately revive shortly after death; at the cost the his 'Life-Force Dragon' Lacrima. Once he had been revived, he headed back to the Magic Slayers Guild in order to prepare its members for inter-guild combat with Fairy Tail, so that he may have vengeance on Gildarts.

The God Avengers
This group of God Slayers each have mastery over elements that other God Slayers have been seen to have. They each hold a grudge toward the previous God Slayers, for they did not learn God Slayer magic from the gods themselves, but were taught by mortals (Zancrow) or from books (Sherria). They seek to kill Zancrow, Sherria and Orga because of this, although they are unaware that Zancrow is already dead, and Sherria has lost her magic.