“You don’t think you hear anything.” I was told this by a Dungeon Master almost two decades ago and it has stuck with me all this time. It is not just the words but the context of the words. This infamous line was said after I had rolled a middling perception roll while on watch.
There are so many variations of this line. If the rogue is sneaking and makes an average roll, as a DM you could say, “You don’t think anyone can hear you as you sneak.” Say a player is suspicious of a non-player character and they roll to see if they are lying. If their roll isn’t high enough to be certain either way, by saying, “You feel like they are telling you the truth,” you will most likely deepen their suspicion.
This particular phrase’s power is derived from your player’s own imagination. It uses the same principles a horror film uses; when presented with endless possibilities often a player will fill that void with their suspicions. Like staring down a dark set of stairs, your fears are made manifest on the canvas of the pitch black. The ambiguity of the phrase is why it works so well.
Why would you use a tool like this while running a game though? The answer is to add tension to an otherwise bland scene. You could say, “You rest for the night.” Or you could have them take watch and roll perception checks. No matter what the players roll, you tell them, “You don’t think you hear anything.” You make them wonder what they could have heard.
Now, this doesn’t always work the way that you want. A misdirection like this could cause the players to become fixated on something you meant to be largely trivial. A suspicious NPC that the players get a mediocre insight roll on could lead to them following them home or interrogating them or not being willing to take a quest from them, which can stall the storyline or annoy other players.
When faced with uncertainty many players will talk through their suspicions with their fellow players. This is when you as a DM have the opportunity to put your players speculations into your narrative. This is a double-edged sword they don’t even know they wield. An example could be that the players are listening at a door and you tell them that they, “Don’t think they have heard anything.” If in their speculation they mention that there is probably a horde of orcs waiting to ambush them just on the other side, what had been an empty room is now a room filled with orcs waiting to ambush them. On the other hand, a room that I hadn’t intended to have treasure will have treasure hidden in it when a player begins searching for it.
In so many ways pen and paper role playing games are collective storytelling. Sometimes subverting expectations can be the spice that keeps players on their toes. Other times, though, letting expectations be the guiding force can lead to satisfying moments. Letting a player proudly pronounce, “I knew it all along” can happen because you let the players guide the narrative without their knowledge. This can be made possible by leaving a level of ambiguity when you answer questions.