Does anyone know how to complete the final castle? The guy in the thrown room ask you to do something. I tried killing all the monsters in the castle, but they respawn and there doesn't appear to be a final boss.
If you've managed to open the path to and talked to the important NPC in the throne room, then-
check the bookshelves in the first floor. One of them should reveal a secret passage. It's a straight line to the final boss afterward.