What's the best trap you've ever unleashed upon your players?

[Khairn]

Here's the scene ...

the party travels down a long corridor, with a pane of glass at the far end that stretches from floor to ceiling and wall to wall. A few feat past the glass is a portcullis with spikes at each intersection facing the pane of glass. Through the glass and portcullis the players can see a large room (50' x 50'). In the middle of the room was the gem (appropriate treasure) that they had been searching for.

The party is appropriately paranoid. So they try to detect, magic, poison, traps etc. All to no avail.

Finally the barbarian decides everyone has put too much thought into this and breaks the glass with his axe.

The room beyond is almost 300' tall and a complete vacum. Everyone including the barbarian failed their strength rolls to avoid being pulled forward and impaled on the spikes of the portcullis. The extra weight of their impaled bodies disturbs the balance of the portcullis causing it to fall forward (towards where the party came from), further impaling them under a few tons of sharpened iron.

Made the GM beam like a proud papa, and to this day the players become insanely paranoid whenever they see a pane of glass.

 

[nethervoid]

What objective does it achieve other than totally frustrating the player as you won't except any of their actions, other than the one solution you have planned?

fun?

 

[Bagpuss]

fun?

Nope I fail to see the fun. Well perhaps if I was the DM and need to cook myself a stir-fry while they tried to solve it, I could just keep shouting from the kitchen "Nope, nope, nope, that does work either, nor that, nope, try again, any other ideas? Nope, no, not even warm." Great fun.

 

[xnosipjpqmhd]

Not so much a trap but...

I like things simple, sensible, and non-magical, like this:

At the end of a long-ish corridor in an ancient dwarf city now occupied by Bad Guys (tm) is a door. On the door, the bad guys (goblins, bandits, what-have-you) have hung an old floor-length mirror they found and/or stole (this also could be a large shield of well-polished steel, or whatever makes the most sense). Behind the door are a few bad-guy guards who are playing cards, sleeping, or whatever.

Heroes who walk down the corridor will see a light source approaching them from the distance. Most likely, they will stop and quickly back around the corner or duck into the nearest alcove, then peek out to see if the enemy is still approaching. They will see that the light source has also stopped and is half-hidden now, as if the enemy is laying in ambush for them. Here follows some clever plan by the heroes to outwit their own reflection. Often this will end with the heroes breaking the mirror (or striking the metal shield), which alerts the guards on the other side of the door, who call for reinforcements....

ironregime

 

[xnosipjpqmhd]

Here's another one I like...

Our heroes fought the guards, but one of them got away. So they chase him up a vertical shaft. About half-way up the shaft, the fleeing guard knows to avoid certain handholds that are either trapped or just crumbling. When the heroes grab these handholds, something bad happens... Maybe the handhold comes loose and the hero has to make a climb check. Maybe old rusty nails stick out from the handhold. Maybe placing weight on the handhold triggers a more elaborate trap. Or all of the above.

Anyway, when the guard gets to the top of the shaft, he kicks a few heavy rocks down behind him. This is actually quite bad for the heroes in the shaft, since they most likely can't see it coming and couldn't dodge it even if they could see it. And the rock has a high chance of striking the hero in the head. Ouch. To top if off, if the first hero struck loses his grip, he tumbles down onto the hero below, and so on.

I like these kinds of ideas because it forces even high-level heroes to think before charging into the lair of a few low-HD opponents.

ironregime

 

[Kid Charlemagne]

I built a pyramid of traps for my last campaign, and it had several pretty decent traps - I'm not really a trap-builder by nature.

My favorite was a room, roughly 40 x 40. Upon entering, the door behind closes, and torches in the room blaze up. Then, at one round intervals, stone walls descend, in a predetermined order, each one ten feet long. And small, flying fire elementals (I think they were firehawks) attack the party, setting them ablaze.

There's a limited amount of time to get to the far door, and open it. Up until the very last round, a path can be followed, but if you wait too long, a wall will drop over the exit door. Dealing with the firehawks is a distraction - they were CR 2 or 3 creatures for a 12th level party - only there to make them waste time.

It was a blast when they'd head down one leg of this maze that was building itself - and their path would be blocked by a suddenly descending wall.

It went over very well.

 

[xnosipjpqmhd]

Here's another great idea... simple and effective. It's not mine; I probably read it on a thread similar to this one a long time ago. Anyway...

Let's say the Bad Guys (tm) are kobolds, gnomes, or other lightweight types. One area of their lair has a section of old floor that is about to give way, but it still seems to be able to support the weight of one kobold at a time crossing it. Painted on the wall is a crude warning (either in the Kobold language, or more likely, in the form of a crude and ambigious pictogram) for the kobolds to cross one at a time. This isn't even necessarily a real trap or intentional defence, but it can cause heartache to players regardless ;-)

Or...

Let's say a few bad guys are guarding a 10-foot-wide passage. They have stacked some stones across the hall as a barricade (providing ample cover against range attacks ;-), with some dry twigs and leaves strewn on the floor leading up to it, so they will hear the footfalls of intruders.

What the heroes may not know is that the twigs and leaves conceal a tattered blanket that has been stretched over a pit. The defenders know that there is a slender ledge on one side of the pit to allow them to cross safely, but it's unlikely that any hero will be able to check for traps so close to the barricade without being attacked repeatedly. Thus someone is likely to fall into the pit, perhaps two or three heroes, if they try to charge the barricade at the same time. Once they've fallen in, the kobolds simply start pushing the heavy stones of the barricade down upon the trapped heroes.

ironregime

 

[Kid Charlemagne]

Another of my favorites is the obvious pit trap, with a relatively easy, ten-foot jump -- and a wall of force (or of thick glass) directly on the opposite side, so that when you jump the pit, you hit the transparent wall, and fall into the pit anyway.

 

[Mark CMG]

Years ago, the day before I was to run the big finale game of a campaign leg I was walking around someone's patio during a visit. At some point it came to my attention that one of the flagstones was rocking back and forth, just ever so slightly, and it humorously reminded me of a pressure plate trap from a previous game. Out of curiosity I lifed the flagstone and found that a single pebble that had somehow worked its way underneath was the cause of the disconcerting stone situation and I promptly decided that it would be, as is, in my next game somewhere along the path that the players would likely take to track down the so-called Big Bad. It was. They came across it, spent over an hour on it, and the BB got away...that day.

 

[blargney the second]

Grimtooth.