“ 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 friendly human hunter has a talk with you about what you are doing here, and how is the weather. He advises you to not disturb the animals, tend to any fire you set, etc. This is actually a werewolf checking his territory, and if you are not to his liking, he may ambush you with his pack later.”
“ The party comes across a nice hermit in the woods. He gives them food and lodging for the night. They awaken to his terrified screams. 'East! It's east! Stop it! It'll kill us all!' The poor horror-stricken hermit dies thrashing in agony, one boney arm outstretched, his finger pointing to the east.”