critical failures that lead to treasure
“Fari! Duck!” Havilar cried. The second head slammed into her side and threw her into the lake. The icy water shocked her every nerve and she nearly gasped in surprise. The blue light of the water was all around her, and for a moment she couldn’t tell where the surface was and where the lake bottom lay. … She turned, trying to find some purchase, some touchstone that would point the way. And found herself facing a dark, jagged hole in the rock. … She ran her fingers over the freezing stone, the chiseled edges of runes still clear. No wonder it had been lost to the ages.
-Lesser Evils by Erin M Evans
It’s often a misstep that leads to a discovery. That’s quite common in adventure novels, and it’s a nice little encounter-design reminder: a dungeon can use a few easter-egg discoveries that can be found only by meticulous search OR by some sort of catastrophic failure. If everything goes well for the party, they’ll probably miss a treasure or two.
The most obvious example of this trope is the treasure or secret door at the bottom of a hidden pit. If you want to strip the idea to its most basic form, the very idea of a monster guarding treasure is central to D&D: you pass through a misfortune to get a reward.
More specifically, here are some situations where a creature’s successful attack reveals an otherwise well-hidden treasure.
A few of the crystals in the chandelier are actually diamonds. If the kobolds cut the rope, dropping the chandelier on top of you, you might notice that a handful of the crystals didn’t shatter on the flagstones.
There’s a glowing dagger inside the purple worm’s belly.
The glass hill is too slippery to climb, but on a critical hit, the angry hill giant hurls you to the top.
The purple teeth of a Night Smiler break off in the wound. Cure Disease will prevent further damage. Otherwise, in the ensuing fever, the bite mark’s pattern of red, inflamed skin spells a password that will let you enter Death’s kingdom alive.
A roc takes you to its jeweled nest.
The halfling squeezes into a tiny tunnel, where he is dragged into a ghoul lair. For as long as it takes them to eat him alive, they crouch on a pressure plate that opens a valve that pours holy water into a sunken bath. Any further living offerings taken by the ghouls will cause more holy water to be dispensed.
If you disregarded the advice of the druid and enter the Oakwood carrying anything made of oak, 2-40 Acorn Men will zip down from the trees and attack, riding holly leaves. Each holly leaf is attached to 1-3 goodberries.
If the Lurker Above is killed while it’s on the ceiling, it turns to stone. Otherwise, when it drops onto its victims, it reveals a planetarium on the ceiling. Touch a planet and you fall asleep for 8 hours or until awakened. While asleep, you have accelerated hex-crawl adventures on that planet: each day of sword-and-planet adventure takes a turn.
If you’re cursed by the water weird, you turn to liquid, flow through the grate in the floor, and drain into a cave, where you re-form next to the ladder of a smuggler’s hideaway containing magic drugs.