The destruction of Hades in the ranking of kings is to prevent monsters from coming out of Hades.

King Perth asked Thomas to destroy the underworld, because all monsters come from the underworld. After these monsters are killed by Deroussy, if there is no entrance, there will be no other monsters to kill Celine.

Because Milan Joe wanted to kill Shirin with magical things, the king of Perth asked the apes to try out how powerful these magical things were, and to measure whether Dorothy around Shirin could save Shirin through his strength.

The end of hades:

The brothers Desha, Depa and Ou Ken in Hades are one of the few normal people in comics. Big brother Desha is a generation of wise masters. After overthrowing his cruel father with his younger brother, he turned the underworld, which was originally like hell, into a rich country where all ethnic groups lived and worked in peace and contentment. However, such a man finally became a homeless man with amnesia, and the kingdom of hades was destroyed with his disappearance.