“ If you want to add a 'supernatural' touch to your campaign, define the rules of magic and the universe. Make your players comfortable with those rules. Then your new supernatural creatures must then break those rules.”
“ The creatures in this dungeon will not become hostile so long as you do not cause any trouble inside. If you provoke them though, you aggro the whole dungeon. If the players are smart, they can complete the dungeon crawl without having to fight anything.”