Lords of the Seven Deadly Sins

Lords of the Seven Deadly Sins are a group of demon bosses from YGGDRASIL.

Background
In the Web Novel, at some point in the history of YGGDRASIL, there once exist a World Champion of Muspelheim who managed to turned himself into one of the Seven Deadly Sins. Thus, his power grew into tremendous might to the point that he could fought evenly against thirty players by himself. He would later be chased by players until destruction, and then failed during the moment of his character deletion. With the character being deleted by the developers, a new tournament which is the Muspelheim festival began afterwards, and the second World Champion of Muspelheim was crowned the first female (appearance wise) World Champion by far.

Strength
The Seven Deadly Sins, being one of the World-Class enemies in the game, even if 30 level 100 players, were fully prepared and forewarned of the battle ahead, did battle with one of these World-Class enemies, the outcome of the battle would still be in doubt.

Trivia

 * If one of these had appeared before them, it would be a threat to all of Nazarick.
 * The are possible based on the Seven Deadly Sins.