The League of Eight were a group of elite dragons who ruled in the original Black Draconium Empire alongside Armeggaddon and The Vysox. They were alive 3000 years ago during the original Dragon-Human War and were among the ones who first started this war, leading all dragons to turn on humans. Today they live as spirits trapped in 8 different Bone-Marks hidden in The Wastelands of Loan. Originally, a map showing the locations of these Bone-Marks was held with the Vysox's Bone-Mark but after Moordryd found this and attempted to obtain them, the gold draconium Dragon Priests intervened and took them all away to a safe location.
As of today, the League of Eight are simply pure black draconium dragons who follow Armeggaddon. It is unknown where these dragons came from; though they resemble the dragons bred by Word Paynn in Episode 24, no pure black dragons were known to have escaped at the end of the episode. The dragons could not have been the original warriors trapped with Armeggaddon either or they would still be the original League of Eight dragons rather than the Bone-Marks we see today. An indication that suggests they are not modern dragons is the colour of their mag streams; it matches the ancient black draconium like that of Armeggaddon, which is a slightly darker purple than that of modern day Black Draconium gear and dragons.