Zarban

In old-school TTRPGs, “listen at doors” was a common thief ability. It even got better as you leveled up, which is kind of silly. But in retrospect, it’s even sillier to restrict it to thieves. A wizard can’t listen at a door?

It gets worse. Real antique locks could accept the key from either side to lock them, but that meant you could see right thru the lock. It was a major motif in a lot of old stories and art. Yet spying on a room thru the keyhole was never a thing in D&D.

But you can make it so it is. Just change “listen at doors” to “eavesdropping” as a thief skill. You can allow any character to have a go at eavesdropping by ear or by eye, but thieves get better at it as they advance in level. This can include things like reading lips as well as spying and listening in on activity or a conversation, sliding a mirror. Give a few opportunities like this to thief players, and they’ll relish the experience. It should even include the skill to drill a tiny hole in a wall in order to have a chance to listen or see what goes on.

Now, a lot of doors won’t have a thru-and-thru keyhole but some other type that doesn’t allow spying. The door may have a bar on one side or a big latch. (Some of these might still be picked by a thief, if they can get a tool thru the crack.)

And those that do have a keyhole should sometimes have the keyhole blocked by a key on the other side or by something tied to the door knob and hanging down or by a little swinging plate meant to defeat spies.

If it’s the key, the players will likely want to try to slide something under the door like a piece of parchment and then poke the key out so it falls on the parchment and can be pulled out under the door. You can plan for that to happen a time or two, and your players will be ecstatic.

You might use the eavesdropping check (AKA the “die of fate“) to determine if spying or listening at the keyhole might yield some information or roll on the table below.

1d6	Can the Keyhole Be Seen Thru?
1-2	No, and it’s a one-sided lock anyway.
3	No. It’s blocked on other side.
4	No, but it’s blocked by its own key or something else that might be dislodged.
5	Yes, but the view is poor or partially blocked or there’s no light.
6	Yes, and the view is good (there may even be light in the chamber).