Type: Test of Confrontation.
This is a perfectly square room with an elaborate trap mechanism which allows all 4 walls to close in on each other without jamming. The mechanism works exactly like the aperture of a camera lens. As the walls close in, the space which makes the room the PCs are in will begin to shrink.
There are multiple applications for this room but in this case I will describe its use as an ancient security system to protect an artifact.
So the PCs enter this room to see the artifact on a pedestal in the center. There is nothing to indicate that there is a trap in the room. As they approach the artifact its pedestal lowers into the ground and the artifact is secured in an underground compartment which cannot be accessed. The doors to the room will automatically lockdown keep them trapped inside. The PCs will not be able to retrieve the artifact nor exit the room until they complete the challenges presented to them.
For each challenge they are given a time limit to complete it which starts the moment it is presented. If they complete it in time, nothing happens and they are given a short breather before the next one is presented.
If the time limit is reached and the challenge is not completed, the walls start to slowly close in for every round over the time limit until the challenge is completed. Once it is completed, the walls stop moving. But they will remain in the position that they stopped in.
Once all challenges are successfully completed, then the walls will move back to their original position, the pedestal will raise back out of the floor, and the doors will open. The PCs will now be able to retrieve the artifact and exit the room.
Some example challenges can include:
Example 1: You are confronted with waves of monsters that spawn in the room with a set time to defeat each wave. Each wave increases in difficulty so the time limit will adjust accordingly.
Wave 1 can have level 1 monsters. Time is 3 min.
Wave 2 has level 2. Time is 5 min.
Wave 3 has a mixture of levels 1 and 2. Time is 6 min etc.
Example 2: A riddle is presented by some means of communication be it text or voice etc. "A treasurer has 3 large chests. One contains Gold, one contains gems, and one contains a mixture of both gold and gems. Each one of them has a label of 'GOLD', 'GEMS' and 'MIXTURE'. But the treasurer says the chests are all incorrectly labelled. How do you determine the contents of the chests by removing only one thing from one of the chests.?" Time is 1 min.
Again, technically you can go over the time limit but then the walls start closing in. So it is best to complete the challenges as quickly as possible to make sure the walls move as little as possible.
The number of challenges to complete is up to the GM.