Four Dragon Lords

The Four Dragon Lords (四竜王) are a sub-group within the Ten Dungeon Marvels comprised of the bosses of floors 96-99.

Background
The Four Dragon Lords were originally Arch Dragons living in the Caanat mountain range. They each evolved into rare element Dragons and after living for hundreds of years, being just on the edge of evolving into a Dragon Lord, they were captured and tamed by Milim Nava for use as floor bosses in the Dungeon.

Trivia

 * Despite guarding the lowest floors, the Four Dragon Lords are ironically the weakest.