The Story of My Favorite Trap

Traps are a classic element of D&D. You walk down a dark dungeon hallway and hear a click as you step on a hidden pressure plate. You only have a moment to react. Will a poison arrow launch at you from a hole in the wall? Will a boulder drop from a hatch in the ceiling? In The World Rune I created something far worse.

The Stack o’ Jell-O

There are probably thousands of traps out there to fill your dungeons with. Some are simple, like the classic arrow trap, and some are cruel and complicated like those in Grimtooth’s Traps. My favorite is one I like to call the Stack o’ Jell-O. It’s beautiful in its simplicity, yet terribly cruel and capable of killing off even high-level adventurers.

The party, level seven, found themselves in a cave deep beneath the city, standing before a stone fortress blocking the way forward. Knocking on the gate and asking for passage, they heard the sound of a lever being pulled from inside, followed by that of grinding gears. But the gate wasn’t opening. It was some kind of mechanism being triggered, and the party realized it might be a trap. They chose to scatter and dodge away in various directions, except Traz, the drow cleric, who squatted down and covered his head. This turned out to be the wrong move as a ten by ten-foot portion of the ground beneath him suddenly swung downward like a trap door, revealing a pit below.

At first, it seemed to be a regular pit trap, about fifty feet deep. But there was something down there, something translucent and barely visible. You guessed it: a gelatinous cube. Let’s have a quick look at its stat block, emphasis mine:

Ooze Cube.
The cube takes up its entire space. Other creatures can enter the space, but a creature that does so is subjected to the cube’s Engulf and has disadvantage on the saving throw.

And engulf says:

[…] On a failed save, the cube enters the creature’s space, and the creature takes 10 (3d6) acid damage and is engulfed. The engulfed creature can’t breathe, is restrained, and takes 21 (6d6) acid damage at the start of each of the cube’s turns. […]

So entering the cube’s space gets you engulfed unless you get out of the way quickly enough. However, since our poor cleric was falling, there was no way to avoid the cube. He was engulfed without a save and immediately took 3d6 acid damage. Unfortunately for him, the cube didn’t do much to stop his fall, and he went right through it. And what was beneath the gelatinous cube? That’s right, another gelatinous cube and another 3d6 acid damage. Beneath that? You guessed it, a third one. I was kind enough to rule that the cubes had slowed his descent enough that he wouldn’t take any fall damage at the bottom.

We rolled initiative, and now our cleric was in quite a pickle. His allies of course started attacking the cubes with their bows, throwing axes, and magic. They could only hit the top one since it was blocking the others, and they couldn’t target Traz with any helpful spells either. And the party would have to carve their way through all three of the cubes before they could reach Traz. Since he was stuck in the bottom cube, he would take 6d6 acid damage on each of its turns without a save. And it would get plenty of turns because gelatinous cubes have a surprising amount of hit points. Eighty-four, to be exact. A terrible pickle indeed.

But it gets even worse. On his turn, he could do little but try and crawl his way out of it. The only way was up. Up into the cube above, which would subject him to the Engulf-ability once more, for an instant 3d6 acid damage. Then he’d have to do it again, and then there’d be no way to go. Unless his allies could kill the top cube, which would only make him sink into the next one for another 3d6 acid damage. To top it all off, he was suffocating.

Three gelatinous cubes at the bottom of a pit trap is such a simple idea, yet the cube’s specific characteristics truly makes the situation the perfect storm of danger. The group realized they couldn’t kill the cubes fast enough and had to get creative. They cast some water spells down the hole, and the water seeped between the cubes and the wall. I ruled that the cubes would float since they’re not very dense. This gave Traz a pocket of water where he could suffocate without his skin melting off from the acid. Then, two other characters jumped down through the cubes, bringing healing potions. They managed to hold their breath long enough to destroy the cubes, neutralizing the acid, and eventually getting Traz back up with some rope.

So there you go. Maximum cruelty with minimal complexity, using nothing but a couple of CR 2 monsters and a hole in the ground. The number of cubes can be altered to suit any level of difficulty. Even with just a few, anyone who falls in will take a crapload of unavoidable acid damage spread over a few rounds, forcing the party to get their friend out of there quickly rather than just attacking as usual. I wouldn’t recommend this against a low-level party since they won’t have a whole lot of options for creative problem-solving. But hey, maybe you’re even crueler than I am.

Enjoy your stack of Jell-O!