All anime and other RPG games has Demon kings in a castle. We don't have one on this game yet

We need Elvia Goblins, Dehkia turos, Elvia Rhutum, Elvia Orcs, Dehkia giants as mobs or summoned by the Demon King when he spawns.

Fighting just world bosses is kinda boring there are no challenge. Most of the time other just hit and hide. It would be good to have boss that spawns mobs that attack player constantly when they spawn.