What does molds, ooze, and lawyers have in common?
They’re all slime.
Not so many to choose from today but in general Oozes are a lot of fun to use. In most of my campaigns they make a few appearances. They can be in a random hallway, drop from the ceiling or maybe inside a pit trap. All great and deadly.
Sometimes the classics are the best. In the case of oozes that is true. My favorite is the gelatinous cube. I think they are just an awesome invention to mess with dungeoneers and to make traps and rooms interesting.
The fun thin about these cubes is that you don’t see them coming. You can walk through a hallway and suddenly you are stuck in a colorless pudding who tries to eat you.
The best way to use them in later levels is in addition to traps. Or a creature that uses these cubes to guard things.
In a one-shot I once encountered a talking gelatinous cube and that was also a lot of fun!
The trap we are talking about can be rather deadly so use at your own risk.
It might not be a big surprise that one of my favorite traps comes out of my favorite Dungeons and Dragons adventure The hidden shrine of Tamoachan.
The will-o’wisp sandbox: In this trap you see a light flickering around the corner, once you come closer the light moves away always staying just out of sight and behind the next corner.
If the party follows it long enough suddenly they step on a pressure plate, in front of them and behind them a stone wall falls down. They hear a grinding sound coming from above them. Roll for initiative.
Lifting the walls self should be a though challenge. A DC of 20-25 depending on the level. After 3 rounds sand starts to poor into the room. Making the terrein difficult to move in. After a few rounds strength checks are needed to move in the room.
To make matters worse after 1 round the light that the party was following. A will-o’wisp moves back in the room and starts to attack to party. Preferably the ones doing the lifting.
The longer they take to find a solution the more dire their situation becomes. The best solution is probably lifting the gate or teleportation. Let the players be creative but it should be a tense and dangerous situation.
I find this trap very thrilling, but it can be deadly make sure you now what to do when the players die in here. Roll now characters, get dig up a few hundred years later, that kind of things.