Ivarage

Ivarage (イヴァラージェ) is a bizarre and mindless entity of unknown origin. It was sealed inside the Spooky Palace by Veldanava after it caused mayhem in the Central World.

Appearance
While Ivarage has yet to be described in any significant detail, it can be inferred from its race to look like a massive beast resembling some sort of mythological creature. Its epithet of "Dragon" and Kumara's abilities being tied to it could be used to extrapolate the appearance of a large scaled creature with eight or more tails.

Personality
Ivarage was originally a being lacking any emotions or coherent thoughts, only moving based on its instinct which compelled it to fight strong opponents and cause mass amounts of destruction. After the events of Royal Capital Disturbance it consumed the fallen souls of Obera's army, inheriting their hatred for Michael and Feldway and beginning the Halloween Carnival. It is likely to develop a wider range of emotions and eventually intelligence in the near future.

Background
Ivarage's exact origins are unknown, with Feldway stating that it had to have come from deep space or to have come from another universe. Regardless of its origin, it ended up on the planet the series takes place on, where it was deemed a threat to humanity and assaulted by the acting Watcher of the time, Feldway. Ivarage proved too strong for Feldway to handle alone, with back-up eventually coming in the form of the rest of the Seven Angels of Origin and Guy Crimson. Together the eight of them battled Ivarage in a three month long assault that destroyed the surface of the planet. While little in the way of decisive damage was dealt to Ivarage, it did eventually escape to the Underworld where it was then sealed in the Spooky Palace by Veldanava.

Trivia

 * Despite being given the epithet of "World Destroying Dragon", Ivarage has no relationship to dragons or the dragon race, with the word dragon not even being invented until tens of thousands of years after its sealing when Gaia was born.