Correct me if I am wrong, but is there not a KBD, KB, Black Demon dungeon in RSC? Maybe it was a different private server made dungeon or something.

Layout of the dungeon was something like this.. down the ladder, the first room you could go left or right and had A LOT of different mining rocks. If you took the left path, you came to a gate that would open to multiple Black Dragons and Black Demons, it also had a KBD that would spawn every 10-15 minutes as well. You could see a group of Hobgoblins that were in a room adjacent the Dragons and Demons.

Please help me out with this, I am going semi insane.