D&D 5E The 200 word encounter that kept my party busy for 3-4 hours

[Ancalagon]

So I'm running this campaign and the party (level 3) are exploring forested ruin. A small encounter kept them busy for the end of one session and over half of another. They found a well with a chest at the bottom and mysteriously clear water. Here are my notes, cleared up a bit for clarity's sake:

F: Well with artifact: A solid, 6-feet diameter well in the middle of an intersection, although the rope/bucket is long gone.

25 feet deep to water table. Well water is exceptionally clear (no debris!), about 4 feet deep. Can see at the bottom a chest chained to the floor (greenish metal). Chain is strong (break DC 20) but lock is not very hard to pick (DC 11), but disadvantage because about 2 feet under water. *however* dangerous because of angry eels! These eels are exceptionally transparent and effectively invisible under water. 10 eels, advantage to attack, +2 hit, ignores shield, 1d4 dmg. AC 12 but disadvantage to hit (check DMG rules under water), HP 8. They eat debris and keep water clear.

Should eels be captured alive somehow, can be processed to make potions of invisibility, so valuable.

Eels can be easily defeated by adding 1 pound of salt to water (freshwater fish). Will start wiggling a bit (troubling surface of water) then thrashing around, then die.

INSIDE CHEST: roll artefact from Yoon Suin. Complexity 7*.

A ring of obsidian, about 1 inch in diameter, polished smooth. There seems to be faint runes buried under the surface. The ring of ponytails can be used to detach someone's hair and attach it to someone else.

* artefacts in Yoon Suin are not uber powerful items, but unique "experimental" magical devices that require experimentation to operate properly. They are valuable as curios, or sometimes for their powers themselves.

The party was unable to figure out *what* the "monster" inside was, but eventually filled the well using their sole magical item: a decanter of endless water. They "attacked" the surface of the water which drew the very aggressive eels to the surface, then smashed the side of the well. On land the eels got covered with dirt (ie visible) and were easily dispatched. They then decided to wait for the water to drain back into the water table to fetch the chest... but of course all this racket attracted attention...

This is the short of it. The long of it was a series of experiments and hare-brained schemes to get to the chest. Hilarious and the party had a great time. I thought I would pass it on to you

 

[RangerWickett]

I like invisible eels.

Once my GM had us exploring a dungeon, and he described a section of tunnel where the floor seemed to have dipped a bit, and it was covered in water. It might only be an inch deep, but torchlight made it hard to tell. We spent half an hour casting detect magic, tossing pebbles, tying food to a fishhook and throwing it in, etc. etc. until finally one PC just got frustrated and walked through the mundane, harmless puddle.

One of my favorite weird encounters was for a low-level party, like level 3. They were looking for weird planar portals (I'd told them portals could be sealed in place of needing material components for magic items, and they wanted a magic bow). They got word of eerie moaning coming out of a cave, like wind was being generated inside. There was a portal to the plane of air in the back of a cave, which had been dug out by an aged bulette. The critter was slow and due to the oppositional elemental nature of its environment (earth vs. air), it could no longer burrow. There was only one entrance or exit to the cave, but inside was a whole network of tunnels the old bulette could waddle through, and its bulk was sufficient to block the flow of air. Otherwise, the wind was too strong to move at more than a crawl. The bulette's armor was impervious to mundane weapons.

The party spent a whole session figuring out ways to lure the bulette down different tunnels to block the wind so they could move faster, then scout the next section of passage and flee before it caught them. I threw in a few scattered treasure caches to tempt the party. Eventually the party figured out the trick -- lure the bulette out far enough so it blocked the cave's mouth, which equalized pressure inside the rest of the cavern. They quickly sealed the portal, then used the magic bow to kill the bulette.

 

[Ancalagon]

The eels kept the water clear by eating organic matter, so the twigs the party would throw in would be chopped into bits and swallowed. The party could then see the bits of twigs moving around in swirling patterns, but couldn't make sense of what was going on...

At one point they threw a vine in, but never bothered to inspect the end of it where they would have seen the bite marks...

The treasure inside the chest is really not that important, it's the mini-quest to get it that matters

 

[Ancalagon]

I like invisible eels.

Once my GM had us exploring a dungeon, and he described a section of tunnel where the floor seemed to have dipped a bit, and it was covered in water. It might only be an inch deep, but torchlight made it hard to tell. We spent half an hour casting detect magic, tossing pebbles, tying food to a fishhook and throwing it in, etc. etc. until finally one PC just got frustrated and walked through the mundane, harmless puddle.

.