My players tell me that the creepiest session I ever presented was the one when they had to travel to the prison plane of Carceri, and we're looking for a Mcguffin in the Bastion of Last Hope.
They went into an inn called The Homely Hostel and were certain that the pleasant-looking gnome couple who ran the place just had to be demons in disguise. Several bedraggled, pitiful people were staying at the inn because they had nowhere else to go in this hellish nightmare of a city. Two of them were beggars in once-regal rags, one was a harsh cold elf woman, and one of them was a little boy who had been accidentally abandoned there by his magician master. The party was sure that they needed to rescue these people from this inn.
I'm sure you all see what's coming, but they didn't.
So while gathered at the dinner table, the wizard casts True Seeing so that she can see what the gnomes actually are. She looks at them and sees...gnomes. She turns to the Fighter to whisper this news, and sees that the "little boy" seated next to him is actually a leering bone devil. She manages a bluff check to keep herself composed, and they all managed to sneak out that night. They had been planning to go to the boy's room that night to rescue him. Narrow escape for them.
There were lots of other things like that in the Bastion of Last Hope, and the creepiness was enhanced by the fact that I had the whole room lit with nothing but red light bulbs. I dunno. I didn't think it would be that creepy, but it gave everyone the willies.
They went into an inn called The Homely Hostel and were certain that the pleasant-looking gnome couple who ran the place just had to be demons in disguise. Several bedraggled, pitiful people were staying at the inn because they had nowhere else to go in this hellish nightmare of a city. Two of them were beggars in once-regal rags, one was a harsh cold elf woman, and one of them was a little boy who had been accidentally abandoned there by his magician master. The party was sure that they needed to rescue these people from this inn.
I'm sure you all see what's coming, but they didn't.
So while gathered at the dinner table, the wizard casts True Seeing so that she can see what the gnomes actually are. She looks at them and sees...gnomes. She turns to the Fighter to whisper this news, and sees that the "little boy" seated next to him is actually a leering bone devil. She manages a bluff check to keep herself composed, and they all managed to sneak out that night. They had been planning to go to the boy's room that night to rescue him. Narrow escape for them.
There were lots of other things like that in the Bastion of Last Hope, and the creepiness was enhanced by the fact that I had the whole room lit with nothing but red light bulbs. I dunno. I didn't think it would be that creepy, but it gave everyone the willies.