D&D General Name a great dungeon room, trap, encounter, or puzzle from a published adventure (any edition)

[Prakriti]

Looking for inspiration. I'll start with two from The Sinister Secret of Saltmarsh:

Spoiler: Area 20. Wine Cellar

The room with the dead body in it. I like the mystery of how it got there, who the person was, and what to do about it. Then, of course, there's the danger of touching the body and provoking the rot grubs within. The players have a chance to avoid the encounter by examining the body from afar and correctly identifying that it's dangerous (I tell my players who succeed on a good Medicine check that the body is clearly infested or diseased.)

Spoiler: The Sea Ghost

...and everything running up to it: deciphering the signaling system, planning an assault, carrying it out, etc. The encounter is especially fun because it takes place in an unusual locale (on the deck of a ship) with lots of interesting terrain features (mast, crow's nest, forecastle, etc.) and different enemy types (bandit mooks, tanky officers, a spell-caster) with potential reinforcements arriving mid-fight (the lizardfolk). This whole encounter is especially good because it contrasts nicely with the more typical dungeon-delving episode that precedes it.

 

[atanakar]

The rotating corridor in B4 Lost City is fun. Characters must rotate the corridor, using symbols, in order to access different parts of the level. It's clever non-linear approach. It is also stressful when the PCs can hear the corridor rotate while they are in one of the areas. Will they be attacked from behind? Or will the corridor stop at another door instead?

 

[Fenris-77]

The whole water level from Ghost Tower of Inverness was very cool. Or at least I remember it as being very cool. My favorite trap of all time though has to be the 10x10' pit trap 30' inside cave entrance A in Keep on the Borderlands. First trap I ever fell into. Didn't die. Laid waste to the Kobolds inside. Awesome. I also remembered to jump it when I did a solo speed run of the module with a higher level fighter. Ahh, memories.

 

[aco175]

Keep on the Shadowfell; I remember liking both the kobold hideout early in the adventure with the room having the waterfall and two entrances to enter. I also liked the last room where you battles the BBEG with the partially open portal.

 

[Giltonio_Santos]

The Roper in the 3.0 version of The Forge of Fury...

 

[atanakar]

The whole water level from Ghost Tower of Inverness was very cool. Or at least I remember it as being very cool. My favorite trap of all time though has to be the 10x10' pit trap 30' inside cave entrance A in Keep on the Borderlands. First trap I ever fell into. Didn't die. Laid waste to the Kobolds inside. Awesome. I also remembered to jump it when I did a solo speed run of the module with a higher level fighter. Ahh, memories.

Inverness was fun. We did it in the 80s using the pre-gen characters and with a timer just like rpga.

 

[jayoungr]

I just (re)discovered this thread. I haven't played or run too many published adventures, but I'll nominate the maze at Xonthal's tower from Rise of Tiamat. I have even run that section just as a stand-alone adventure for a different group.

 

[Shiroiken]

In Tower, Temple, and Tomb (2E) there was a particular trap that was... hilarious. The party enters a large hall through and archway, with several doors leading off of it. Each of the doors are trapped, but does not trigger if the find/remove traps roll fails. Instead, if any of the doors are opened while the trap is active, all hell breaks loose in the room, with spears, arrows, fire, etc. hitting every single spot in the room... except the space in front of the door. It was a reversal on the common trope "you said it's clear, so you open it" mentality often thrown at the party's thief, where the thief is perfectly safe, but the party gets screwed!

 

[Eltab]

I really enjoyed the 'thirsty trap' well in the "not-Egypt" tomb chapter in Rise of Tiamat. That whole dungeon (as designed by the loremaster NPC, not the subsequent add-ons) was fun to see the PCs work through.

 

[Levistus's_Leviathan]

In Tomb of Annihilation, there's a trap that makes you fall into a rotating room filled with a ton of deadly traps. It is difficult to get out of, difficult to disable, and I've always wanted to use it in a dungeon.