“ 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.”
“ A powerful wizard that the PCs encounter is completely silent. He does not speak and cannot be heard as he moves. Even his spells are silent, but his magic is just as potent.
He has a tendency to summon invisible chairs, place foes in invisible boxes of force, and other 'mime tricks'.”
“ What if you send the players in a dungeon that was already raided? Maybe you could have traps that are already set off, or the corpses of monsters etc.”