The Dragon race is a class where formidable bosses can be found. Enemies that belong to this class are weak to Dragon Killers. Notable Dragon Bosses include Tiamat, Shinryu, and the Esper Bahamut. Dragon Killer skills are a passive effect when equipped by a unit.
To find the killer gear for the Dragon race click here to open the Killer Gear Finder
These trial bosses can be found in the Vortex. The Esper battles can found in the world map. See wiki page for more details.