Your Worst Deathtraps

[Shining Wrath]

A simple 10'x10' pit trap, 20 feet deep, with a gelatinous cube at the bottom of it.

One of my fellow players says if you drop a rock into a pit and hear "splort", run.

Also, look up. Falling gelatinous cubes are NASTY.

[Phelix-Mu]

Large cavern room which characters enter halfway twixt floor and ceiling, through the only entrance. Except for a series of 10'x10' pillars at 15' intervals that extend halfway to the ceiling (one of which has collapsed and forms a little log-like island below), and a 20'x20' platform in the middle, the rest of the room is flooded with murky water.

Except for a half-circle island along the back wall, about 80' away. There the characters see a series of three, closed stone sarcophagi, surrounded by dozens of lesser coffins propped up against the wall.

Surprise #1 is that the water is full of vampire spawn, and is just deep enough to conceal them, but shallow enough that they can climb/leap out without much difficulty.

Surprise #2 is that the water is unholy water.

Surprise #3 is that several of the vamps are running divine interdiction, which severely hampers all the turn undead resources the party brought along to handle the vamp threat.

This was the scene of one of the most epic staggered retreats that any party that I've run ever attempted, as they struggled to get the five of them, two cohorts, and two npcs out of the room, with three of them unconscious/disabled at that point. I was gunning for a very challenging fight, but it was a series of really bad luck events that turned things from a stiff fight to a likely TPK. But, to the character's credit, they marshaled their resources, came up with a plan, retrieved the fallen, and held off the enemies long enough to escape. I definitely considered it a result.

[atemu1234]

One of my fellow players says if you drop a rock into a pit and hear "splort", run.

Also, look up. Falling gelatinous cubes are NASTY.

Half-Demon Half-Dragon (Red) Sentry Gelationous Ooze with ranks in climb, jump, and balance. And max advancement.

In other words, if you see it, your DM hates you.

[Khosan]

Half-Demon Half-Dragon (Red) Sentry Gelationous Ooze with ranks in climb, jump, and balance. And max advancement.

In other words, if you see it, your DM hates you.

Hide and Move Silently too. Probably Disguise too, depending on whether or not it can disguise itself as a wall.

[atemu1234]

Hide and Move Silently too. Probably Disguise too, depending on whether or not it can disguise itself as a wall.

And Ability focus feats on its abilities, because you hate your players.

[FearlessGnome]

I have something planned for a tabletop campaign I'm running. In a room that is clearly the end of the disappointingly-and-suspiciously-empty cave, there is a fountain that pings as evil. The fountain is very deep, and at the bottom a tunnel leads off to the side and into mundane darkness. The walls are stone, but there are many out of place wooden beams along the tunnel. At the end of the tunnel there is a series of locks that, yes, you probably could pick or smash your way through in a minute or so. But the tunnel is covered in antimagic sigils, and the wooden beams are there to give the low CR intelligent undead somewhere to hide until you have swum all the way to the end of the tunnel. You are starting to run low on air.

And then the grapples start.

[Fosco the Swift]

I must say that I am a big fan of this one! Mind if I appropriate it into one of my games?

Of course not! Hope you have fun with it. And in turn do you mind if I give your trap a go? I've got a specific set of people in mind who will stare at me when they find out all they needed to do is jump

Spoiler: The Room and the Magic Missile

Show

A new meaning of slow death, just to show up Edgar Allan Poe. One 30ft by 30ft by 30ft room. No doors. No exits of any kind. One pillar in the middle. Every minute, every person is targeted with a Magic Missile originating from the pillar. The room is permanently dimensionally locked. The PC's have full access to shield, cure spells and the like, but they won't last as long as the pillar (it's hard to sleep when you keep being hit by magic missiles: no new spells). To leave: simply ask out loud, as the character "May we please leave?" To really mess with them, wait until they use "May", not "Can". Grammar matters you know

[Andorax]

Let's see if I can recall this properly. Inflicted this on my gaming group for a one-off 15th level campaign. Better prepared, they could have easily circumvented, but it caught them off guard.

10' square lengthy corridor ends in 10' stair down, then a vertical 10' shaft both above and below, another 10' stair up, and a door at the top of the stairs.
____| |__
___ _|
\ /
| |

Shaft below drops 100', with sharp, long spikes at the bottom. Shaft above goes up 100'.

Open the door, and the chamber beyond...is filled with water. So it pushes anyone in the stairway down into the pit, overcoming flight by sheer mass and shoving the PCs down the 100' pit and onto the spikes. Ouch.

1 round later, reverse gravity triggers and the door relatches shut. PCs and tons of water fall upwards 200', and so, too, do the spikes that are merely socketed into place, not solidly affixed to the floor. Double ouch.

Of course, there are small holes that the water can drain through in the ceiling, allowing it to pour back into the chamber beyond the door. After another round has passed, the water has drained back to its original spot, and the reverse gravity...cuts out. Spikes (and PCs) proceed to fall 200' once again.

This cascade of water notifies the local golem/summoned critter (I had a spined devil on detail for this) to take the secret tunnel out and around and start resocketing the spikes back into their proper places.

[DM Nate]

You know, there's a fine difference between "appropriately-CR'd trap that can easily kill a group of people who don't work together" and "trap that summons Orcus."

[Mr Adventurer]

Also, the standard Wail of the Banshee trap in the DMG is CR 10.

[atemu1234]

You know, there's a fine difference between "appropriately-CR'd trap that can easily kill a group of people who don't work together" and "trap that summons ORCUS!"

Totally want to make that now.

[SamsDisciple]

I wasn't even there for this session but my brother ran an adventure where the party needed to hire a paranoid gnome wizard to help with an assignment they had but when they arrived he ran down a flight of stairs into the basement. The hallway led to a split level. Downstairs was a simple square grid with many intersections, not very deadly, but it took the players a long time to figure out. There were only two simple traps that were repeated several times, a reloading dart trap that only dealt 1d4 damage, and a ghost sounds trap so they always heard the gnome running away down the next corridor they ran around getting plinked with darts for a good hour before someone decided to go upstairs and find the gnome sitting in an easy chair sipping tea! And yes they even split up to try and corral him into a corner once they found one of the corners.

[Ferronach]

Of course not! Hope you have fun with it. And in turn do you mind if I give your trap a go? I've got a specific set of people in mind who will stare at me when they find out all they needed to do is jump

Thanks :)! Sure thing! Make sure that eeryone is either capable of jumping the required 5 feet or that someone else in the party can hold/throw or otherwise get them high enough up to escape the localized gravity.
Also make sure to keep track of the precise height of all players, items, and familiars. If they are getting close to dying, you can discreetly make a roll and inform the 7foot 1/2 orc that his beard and hair feel funny. A flying familiar can pose a problem in this room (so can flying PCs)... akthough you can always alter how "high" the gravity goes XD