I'm going to combine this with another prompt for designing dungeons:
Essentially, the mechanic (puzzle) should be incorporated and inform all parts of the dungeon from encounters to puzzles to strategy.
Puzzle questions:
1. Which aesthetic are you targeting?
Narrative - game as drama
2. What are the elements of the puzzle?
A beginning/incitement, middle/conflict, ending/climax, resolution
Secret story from campaigns history
Beginning/incitement
Characters need an object or weapon thought to be located in a warded and unassailable dungeon.
Opening the dungeon requires 'fear' so each character present must get into the mindset- centering a phobia, a nightmare, a terror in minds eye.
Categorizing those player inputs according to a table determines the form of the final conflict.
Middle/conflict
Characters proceed through various chambers each with choices or encounters.
What characters do, their combat tactics, are categorized. Use a particular element or weapon type? A certain strategy?
Did the characters choose to pick an electric lock or squeeze through a low circular tunnel?
Did characters use fireball on constructs that assailed them? Or did they use stealth and avoid?
Characters should see hieroglyphs or runes and when inspecting, should need to as a player decide certain meanings or images.
These choices inform the behaviors of the final conflict, it should be the opposite of what players do: if they used fireballs, immunity to fire damage. If they talked through a rp encounter, using words might open them up to hypnotic domination.
Ending/climax
Chambers lock themselves behind players. It should be indicated that they cannot return if they turn back.
The deeper they go, the more powerful, strong, fearsome the final conflict will become.
In reality, the puzzle are chambers in series, that create a creature more and more powerful the further players proceed and draw on their fears.
The solution is to stop digging.
Resolution
Players return to the opening chamber and face the sum of their fears.
It is an illusion, fortunately, though damaging until it's revealed to be so.
The fearsome creature fed on their fears and through them was given life and now exists in the world.
The players have their object, made powerful through an offset of the fear and negativity they released and invested in the artifact/weapon.
3. What clues do the players have to the solution?
a. In the puzzle itself?
The puzzle eventually repeats on itself indicating that quitting is the only way out.
b. In the environment?
Glyphs and warnings indicate that nothing of value is there, to turn back now.
c. In your world building?
Prior character knowledge should inform character choices, either in knowledge checks or previous encountered lore.
Some things are best because they are forgotten. Imagining some forces makes them real in the world, when they should be left unbothered and hidden.
4. Why do the players care about the puzzle?
The entire puzzle recounts a secret story from the campaign history. It's partly intended to get some of that juicy lore in front of the players. Narratives appreciate the context and deepening of the campaign especially as it lets them relate to the ongoing story.
There should be some mystery from the past that hinged on some mysterious force; understanding it should solve a current campaign problem, but as indicated, exploring the darkness of the past will make a potentially worse issue come to be.
5. What are some things that make the puzzle less of a slump for players with different expectations?
Everyone participates, it's something of an expressive puzzle as the characters are generating a monstrosity.
6. You do you
Choose the form of the destructor