One terrifying encounter could be when the party stumbles upon a haunted mansion. Inside, they face ghosts that can possess their bodies. The players have to constantly make will saves to avoid being controlled, and the feeling of losing control of their characters is truly horrifying.
The DM can use ambient sounds. For example, playing creepy music or the sound of howling wind in the background. It immediately sets a spooky mood. Also, describing the environment in detail. Saying things like 'The walls are slick with an unknown slime, and a cold draft seems to carry whispers of the dead' can make the players feel uneasy.
One common DND horror story is about a party entering a haunted mansion. They thought it was just a simple exploration but soon realized the rooms shifted on their own. Traps kept springing up and undead creatures emerged from the walls. It was a terrifying experience as they struggled to find an exit while being constantly attacked.
There was this DM who seemed to have a personal vendetta against one of the players. He would constantly put that player's character in impossible and unfair situations. The rest of us felt really uncomfortable. Like, he made the character face an enemy way above their level just because he didn't like the player. It completely ruined the collaborative spirit of the DND game.
In a DND party I was in, we had a cleric who was not very experienced. We were in a dark forest and he tried to use a powerful healing spell to revive a fallen comrade. But he misread the spell and instead of healing, it summoned an evil spirit. The spirit started to drain the life force of all of us. We were so scared and confused. We tried to fight it, but our attacks seemed to have little effect. Eventually, we had to flee, leaving behind some of our precious items in the process.
There's a r dnd horror story where the players entered an abandoned temple. The moment they stepped in, a feeling of dread washed over them. The carvings on the walls seemed to move in the corner of their eyes. Strange noises echoed throughout the halls. They encountered a series of puzzles that, if solved incorrectly, released more horrors. Eventually, they woke up a mummy lord that had been slumbering for centuries, and it was a fight for their lives as the mummy lord had powerful necromantic abilities.
One horror story was when a player completely ignored the party's plan. We were sneaking into a castle, and he just charged in yelling. It alerted all the guards, and we were almost wiped out. He thought it was funny but it ruined the whole mission for the rest of us.
A common one is when the DM railroads the story too much. The players have no real agency. They are just being pushed along a pre - determined path. For instance, no matter what choices we made, the DM had a set outcome in mind and wouldn't deviate. It felt like we were just puppets in his story.
Dark and spooky locations are common. For example, old castles, haunted forests, or abandoned asylums. Another element is the presence of undead creatures like zombies, skeletons, or ghosts. Curses also play a big role. A character might be cursed by an evil witch or a powerful artifact, which brings all sorts of misfortune and horror. And often, there's a sense of isolation, where the adventuring party is cut off from help or civilization.
The transformation elements can be really scary. For example, when a furry character starts to change against their will, like their body parts mutating into something grotesque. It's a violation of their self - identity.