I just had to post this.
Our level 8 party of would-be dragon slayers (druid, cleric, rogue, sorcerer, barbarian) were making our way through the winding corridors of ancient dwarven caves which were part of the system of caverns that had been taken over by a dragon.
After making short work of a dragon-mutated troll and a dragon-mutated minotaur, among other things, we finally hit our most challenging encounter.
The hallway of death.
So after dispatching some bizarre half-lizard woman we worked our way through a series of corridors, traveling along them using the "right hand rule" to ensure we didn't get lost. Eventually this led us into a tunnel that grew more and more constricting, until I began to get worried my tiger wouldn't fit.
Right at the tightest point, the GM suddenly announced to the rogue leading the way that he needed to make three balance checks (acrobatics skill). The rogue easily passed them.
None of the rest of us did.
So when the barbarian attempted to move through the same corridor and failed his balance check, he fell against the wall and knocked the entire wall down, revealing a thirty foot drop, into which he promptly fell.
After he climbed up the other side, taking a rope along with him the rest of the party attempted to cross what was now a thin ledge using the rope.
Every one of us fell. On average we only took eleven damage each, but the process took half an hour to resolve.
It ended up being the most time consuming and damage inducing encounter of the night.
Yes, I know there are some rules questions here that could have been raised, but frankly it was so friggin' hilarious that none of us cared. Stupid hallway of death. :)
Im sure most of you are familiar with the module "The Sunless Citadel".
The first group I ran it for almost had a TPK that was pretty funny. I will explain in the spoiler below!
The 4 party members where all level 2. The Ranger decides to jump across and fails miserably landing in the spike pit and taking damage. Afterward the Barbarian tries and fails falling beside the Ranger. Then comes the Fighter who EXACTLY meets the DC so he is standing on the opposide side ... where the quasit pushes him off into the pit on top of the Barbarian and Ranger. I rolled and he fell on the Ranger. Now the fighter and the Ranger are in the negatives and the Barbarian is almost dead and has zero ranks in climb.
Thankfully the barbarian raged, choped away a space so the cleric could jump down and he healed the ranger who damaged the quasit enough that he ran off.... but all in all I almost had 3 party deaths from a CR 1 Spiked Pit. The entire group was laughing so hard it was hard to finish the fight.
I thought perhaps you were going to describe the "onion chopper" (as our party called it) from the World's Largest Dungeon. *grin*
Our DM at the time took part of the dungeon and placed it in his homebrew world. Our party was crawling through it for some purpose or other. Every time we encountered some nasty trap there was 0 reward for doing so (even going so far as to put a cursed sword as "treasure" for one such set of rooms).
So when we got to the "onion chopper" hallway (as we called it) we all looked at each other and said "F it, we're not going down there" and went back. I have no idea how bad it truly was. The DM never clued us in, hehe.