Hello all! I'm always trying to come up with new puzzles for my games and r/dndbehindthescreen has been very kind to me for inspiration and when I don't have enough time, so I'm finally going to start giving back in force!

This is a series of thematic puzzles I ran a few weeks ago and haven't had time to write up until now. My PCs were level 3 at the time they encountered this puzzle. It's a bit long and each of the puzzles theoretically COULD be run independently, though without context it might feel a little bland or forced.

The Context

My PCs were going into an old abandoned research facility. I had thematically made it an alchemists' lab, but they didn't know that coming into it. I had other flavor that is relevant to my campaign, but not relevant to this puzzle.

The Buildup

During their climb up the mountain to find the facility they encountered a Displacer Beast and fought it. The area is not known for magical beasts, so already their caution was piqued.

Upon entering into the facility they encountered a recently dead humanoid figure. A high enough medicine check along with their previous encounter with the Displacer Beast would show that the figure was killed by a Displacer (My PCs, however, did not roll high enough to determine cause of death). Upon this dead figure's body was ceremonial dagger and a journal that read:

Entry 1:

I managed to sneak through the forest unseen. I hope. At least, no goblins pursued me and I don’t feel like I’m being watched. Next up is to find that cave.

Entry 2:

I fear I have come this far for nothing. This contraption in front of me confounds me and I’m starting to hear noises at night. I already disarmed the trap on the chest, and I believe the gems inside to be some sort of “key” to unlock the door, though I’m not sure what the dagger is for. The method for disarming seems fairly straightforward--it’s probably just a precaution to keep idiots out.

Entry 3:

I placed the red gem into the slot below the symbol of fire, the blue gem into the slot below the symbol for water, and the green gem into the slot below the symbol for earth, and the white gem in the slot below the symbol for sky, but the main door remains closed! That combination did cause one of the side doors to open. I looked inside and there was nothing but a strange runic circle on the ground. Am I missing something?

(the rest of the journal is too stained in blood to read)

*Edit: Addendum to Entry 3:

*I placed the red gem into the slot below the symbol of fire, the blue gem into the slot below the symbol for water, and the green gem into the slot below the symbol for earth, and the white gem in the slot below the symbol for sky, but the main door remains closed! That combination caused one of the side doors to open and I ran. Maybe I'll try to sneak in tomorrow and try again.

The First Puzzle

The PCs then travel down a short winding path deeper into the cave structure and come across a man-made chamber 30 feet deep and 20 feet wide.

At the end is a large door with four symbols, each with a circular slot beneath them and four colored gem stones (red, blue, green, white) laying across the ground.

On the right is a chest, already open with its contents missing. Any further investigation of the chest will reveal that scrawled across the bottom is text that reads. This is a clue that the dead person above missed.

The blood of man soaks the ground
The ground feeds new life
New life rises to touch the sky

*EDIT: since there's some dispute about this first puzzle I'll put in a more straightforward version that I came up with:

Water soaks the ground
The ground feeds new life
New life rises to touch the sky

*END EDIT

On the left are three large stone doors, one of which is open. Investigating the open door will show a deactivated magic circle inscribed on the ground. A high enough Arcana check will reveal that it was some sort of stasis field. (This is where the first Displacer Beast came from)

The Solution

A high medicine, arcana, or history check will reveal the nature of each of the symbols. A mid-range check will reveal the nature of fire and air, making the logical leap that the opposite symbol is the opposite element is up to your players.

Each of the four symbols corresponds to an element from the alchemists table. The players must place the gems IN ORDER (optional, depending on how nice you feel) into the correct slots.

• Blue (water) goes below the Earth symbol (The blood of man soaks the ground)/(*Water soaks the ground)
• Green (earth) goes below the Fire symbol (The ground feeds new life)
• Red (fire) goes below the Air symbol (New life rises to touch the sky)
• White (air) goes below the Water symbol (Deductive reasoning)

Any other solution will cause one of the side doors to open and release another Displacer Beast. Failures after two will result in nothing happening.

When the correct solution is implemented the door will spit out the gems and open to reveal a well-tiled hallway 15 feet long that opens up into a larger laboratory-esque area. (The hallway is trapped)

Traps!

The tiling on the floor is pressure sensitive (40 lbs). Walking on a pressure plate will shoot a toxic dart from the wall (Dex save DC 13 or 1d8 poison damage Con save for poison).

High enough investigation will show the correct path to walk to avoid the pressure plates, or with trial and error they can push down on them while being careful and take about 10-15 minutes to determine the correct course of action. (My PCs were currently being pursued by something, so they didn't have that time)

The Alchemists' Lab (Puzzle 2)

You are greeted by a large 'L' shaped room sectioned off into three distinct areas. Closest to you on the left there are empty vials with tubing strewn between them. On the right there are a series of wood cabinets. Further back on the right are rows of books and scattered notes. There appears to be a door of some sort with a viewing slot on the back left.

Front Left

This is mostly flavor. If they want they can acquire 'x' amount of alchemical kits (I let them have four)

Front Right

The cabinets are mostly empty except for four vials of liquid. One red, one blue, one green, one white

Back Right

I put in more flavor texts for my world here along with a note (I made a version of this by hand). If you want to add some red herrings, search "Alchemical Symbols" and have fun.

Back Left

This is an "experiment room", cordoned off from the rest of the area. There's a single slot in a thick stone door that allows people to peer inside. They will see a clean room with a large, cracked bowl sitting atop a pedestal. If they enter the room they will see the bowl has the word "SA--" carved into the side, but the portion of the bowl that contained the remainder of the word has fallen off (for context, the entire word reads "SALT". I made props for this puzzle so the visual was a piece of paper that I had just torn the 'L' and part of the 'T' off of).

Mending the bowl will reveal the full word, or a good investigation will allow the PCs to find the broken piece of the bowl and fit it back together.

The Solution

The correct way to make salt, according to the alchemical notes, is to combine water and earth. Pouring these two liquids into the bowl will result in sizzling and vapor rising from the mixture and then salt forming on the bottom of the bowl. Then the wall behind the pedestal/bowl will open into a secret chamber.

An incorrect mixture requires a Dexterity Saving throw (DC13) or being blasted with fire/acid/cold/etc for 2d6 damage. Or whatever you want, it's fun with chemistry.

(Again, I made props for this by dyeing four vials of liquid different colors. In the blue one I put baking SODA, in the green one I put lemon juice. The result is the mixture fizzling like soda for a few seconds.)

The Secret Room (Puzzles 3 4)

You can make this room look like whatever you want, but it should be small and secretive. (Mine was a rectangular table with eight chairs surrounding it. The walls are intricately painted to show each of the ancient Seven Heroes of my world, each one standing behind one of the chairs save for one.)

On the far side of the room, on the wall, there is a small (1x1) square of discolored stone. Pushing on the stone does nothing and it is immune to magic.

High Investigation will show that there are faint traces of blood on the discolored stone.

High Arcana or Religion will reveal that the stonework is indicative of some sort of sacrifice.

If they get frustrated, remind them they have a ceremonial dagger that they haven't done anything with yet.

Smearing blood onto the stone will cause it to vanish (My PCs decided to use the old, dead body they found up above and smear his blood across the stone),

Inside is an alcove with two boxes, one small and one larger. The smaller one contains a script that reads

Water quenches fire
Sky falls to the earth
I seek what I desire
I claim this new rebirth

(Note that I wrote the above in a different language, so it added another layer to the puzzle)

The larger box has no visible seams or method of opening, but has four circular slots identical in size to the gems that were used to open the door. Two slots are together on one side of the box, two slots are together on the other.

The Solution

This has two parts:

1. Blue and red must be placed together (water quenches fire), white and green must be placed together (the sky falls to the earth). Upon this being correctly established the gems will be sucked into the box and the alchemical symbol of creation will appear on the top of the box. (there are lots of different interpretations, but I use a simplified version of this. Glowing not required)
2. Any party member must speak a true desire of their character (I seek what I desire). Part two may be omitted if the players are getting frustrated or you feel like they won't solve it. (As a hint for this one I had them roll Int checks. On a 10 they understand that they fulfilled the first part of the poem/riddle, but not the second)

When the puzzle is solved the box will open to reveal whatever loot you decide to put in it. For my campaign they found a small, coaster-sized disc with the alchemical symbol of creation on it. One of my PCs promptly grabbed it and the symbol was branded onto his palm. Now he has extra magic with bad consequences and weird side effects.

ALTERNATELY (If you want to put the symbol of creation in the box): When the first part of the box-puzzle is solved the box will open, but will be empty. Looking into the box will make that character roll a Wisdom Save (DC15) or be paralyzed for an hour. Those characters who look into the box will be assaulted by pure information. (This is the version I used to add extra confusion at the empty box). Any objects placed in the box will dissolve and be absorbed/evaporate to leave the box empty. If someone wants to TOUCH THE INSIDE OF THE BOX (DEAR GOD WHY) they will take 1d6 pure arcane damage per second they are touching it. Extended contact may result in loss of whatever they were touching it with.

Problems I Encountered

This went pretty seamlessly. There was an aspect of urgency that disallowed my PCs from just sitting around and deliberating all day, and as relatively intelligent people they didn't encounter any long-term frustration until the very end when they got to the box and couldn't figure out the second half of the riddle. They argued for a while until someone finally shouted out "I DESIRE TO KNOW HOW THE FUCK TO OPEN THIS BOX"... which at the time was a true desire of his character, so the symbol of creation appeared.

They did want to try to open the two side doors (that held more Displacer Beasts), but since they solved the first door without incident those two remained sealed away.

*thank you u/deathmon44 for the shiny!