D&D one shot - The Mystery of Hadal Mine
Here’s a horror one-shot I ran for Aimee Carerro to help her get used to the game before her iconic run on Critical Role! The stats are for 10th level characters, but you could edit the stats and use the same setting for different leveled characters. This is made to be played in a few hours.
SETUP: There’s a mining settlement in desert canyon country. Hadal Canyon: a very deep canyon with red rocks, cacti, and shards of crystal spiking out of the earth. Hot sun and cold shade.
Your group was hired because no one has heard from the settlement for a while. The settlement is mining rare jewels, so they will be paid well.
Start outside the canyon, heading towards the settlement. A high perception check will show prehistoric shells in the sand.
Players come across the settlement, which seems abandoned at first, but by poking around they find an NPC (they notice smoke coming out of the inn)—it’s Louis, the innkeeper, who can tell them a bit of what happened:
All the miners came back from the mine for the day, like normal…but they seemed odd and out of it. None of them said much. Overnight, their eyes started glowing black and they started talking in a strange language. They all got up, filled canteens and buckets with water, and went back to the mine. They seemed to be almost…possessed?
Louis’s husband Victor is one of the miners, so he wants to get him back!
Louis has Bandit stats (Monster Manual p. 343).
ESCORT MISSION/ENCOUNTER: Louis is guarding a few kids who work for him: Starga and Bessie, two girls whose parents work in the mine. They’re the only ones who weren’t in the mine. 10 HP each. They’re hiding out because:
The village is being attacked by weird beasts—pack animals that were possessed!
Louis asked the PCs to get the kids to a cart elevator that will take them up and out of the canyon. To do this, they must get the winch key from the toolshed and then fight their way to the cart elevator. It takes a full minute to crank up the winch before sending the kids up to safety.
Louis will stay behind to help them figure out what is going on. He doesn’t want to abandon his husband down there!
Monsters: three of them. They look like fucked up donkeys, still with the remains of harnesses and saddlebags on them. Their eyes are glowing milky white and their legs bend the wrong way. Barnacles grow on them and they almost seem to float. Burbling noises come out of their mouths like they’re drowning. They have tentacles that come out of their mouths.
Use GRELL stats (MM p. 172).
There’s also a similarly-fucked-up canary that just flutters around.
PCs can heal them of this possession with: Dispel Good and Evil, Break Enchantment, Hallow.
PCs can all fight them with brute force. If they reduce them to 0 HP and then heal them (by any means) they will be restored to their normal donkey selves.
Time to ENTER THE MINE!
They head into Hadal Mine, led by Louis. Almost immediately it becomes completely dark. You can feel the weight of the earth above you. As you go deeper, it gets hotter.
There’s an eerie whisper in an unknown language echoes through the halls. If someone can translate, it says this repeating phrase: As it once was, so it shall be again. Though a millennia of stone has settled over my resting place, though the waters have long since boiled away, we shall return. The deep dark will return. The sunlight will never reach us. The air will never touch us. Bring me water. Bring me water. Bring me water.
They find one of the possessed miners in here, her eyes blank, glowing black. She’s stuck, foot caught under a wooden beam, and mumbling the phrase over and over.
She’s carrying a pitcher of water—if they spill it, she will pull herself free (hurting herself in the process) and attack. If they free her from where she’s trapped, she’ll stumble deeper into the cave, ignoring them, and they can follow her.
(Miner stats: Cultist, MM p. 345) PCs can heal her from this possession with: Dispel Good and Evil, Break Enchantment, Hallow.
PCs can fight her with brute force. If they reduce her to 0 HP and then heal her (by any means) she will be returned to herself, a confused and scared mining woman who doesn’t remember the last twelve hours.
They can take an elevator down, or find their way through one of the natural cracks. These are close and jagged. Fossilized shells and aquatic animal skeletons on the walls.
They eventually discover the LOWER LEVEL:
Mining stopped because they broke through the wall into an ANCIENT TEMPLE!
The first thing you notice is that the hot, close air of the mine suddenly becomes bone-chillingly cold. The close walls of the mine tunnel/cave open out into a vast chasm. Fossilized coral and shells coat the floor, laid out in intricate, hypnotic patterns. Whorls of glowing ore sparkle on the ceiling, walls, and floor. It seems as though light reflects off water, shaking on the ceiling, although there’s no water to be seen. You can hear faint chanting.
Right away: You realize the pillars around you are not naturally formed—they are carved into the ancient, weathered shapes of aquatic, vaguely humanoid creatures. Squirming tentacles, long teeth, scales and fins. The eyes are what draw you in, though—wide eyes carved out of matte black stone.
When they enter the Temple, have everyone roll a Wisdom saving throw (DC 18). On a success, nothing happens. On a failure, the PC hears the whispering voice in their mind, but now they can understand it. They are commanded to walk to the inner chamber, and to get any water. The spell lasts until they take damage and snap out of it. (The spell is Dominate Person.)
As they look around: Through a narrow opening to the left, you see something glittering. The luminescent ore flickers over a wealth of treasure. Rough cut gems, inlaid weapons and statues, crowns, jewelry, tablets carved with runes, everything shimmering with mother of pearl and pearls and gold and fiery opals. The treasure of a thousand kings.
All the treasure is enchanted. Touching it will trigger ANIMAL SHAPES. Roll a d4. They turn into 1 – hunter shark (suffocates after 3 minutes) 2 – giant octopus (2 minutes to suffocate) 3 – chuul (amphibious; doesn’t suffocate) 4 – giant seahorse (1 minute to suffocate). Stats replaced by animal stats, although INT, WIS, and CHA remain. Any damage taken is dealt when they turn back. Will turn back when they reach 0 HP, or when they are freed by some spell.
When they turn back, they still have the treasure, and now it’s un-enchanted. Roll on Magic Item Table B (Dungeon Master’s Guide p. 144).
Continuing to look around: Through a narrow opening to the right, your eye is drawn by a beautifully inlaid mosaic made out of colorful color and mother-of-pearl. If you investigate, it seems to show an underwater scene: a great four-armed, shark-tailed figure inlaid in gold, dolphins and fish and sharks swimming around her, and crowds of supplicants that look like fish-people.
If they look at it enough to see this, roll a Wisdom Save DC 18. On a success, nothing happens. On a fail, they are drawn forward: You realize that all the figures in the mosaic are facing one way. You follow their gaze and see a dark spot on the mosaic – or is it a pit? You are compelled to use your action each turn to walk towards it.
Taking damage will break the spell.
If they reach the pit, they fall forever.
Walking towards the chanting sound, they enter Hall of Horrors. The chanting is stronger, and you see a shivering glow that indicates some shit is going on down this hall, which is tiled with spiraling black patterns. You can avoid stepping on them with a DEX DC 13 save.
Stepping on the black tiles casts Evard’s Black Tentacles (PHB p. 238): Squirming, ebony tentacles fill a 20-foot square on ground that you can see within range. For the duration, these tentacles turn the ground in the area into difficult terrain.
When a creature enters the affected area for the first time on a turn or starts its turn there, the creature must succeed on a Dexterity saving throw or take 3d6 bludgeoning damage and be restrained by the tentacles until the spell ends. A creature that starts its turn in the area and is already restrained by the tentacles takes 3d6 bludgeoning damage.
A creature restrained by the tentacles can use its action to make a Strength or Dexterity check (its choice) against your spell save DC. On a success, it frees itself.
The spell lasts for one minute.
Once they’ve made it through this…The hall bends to the right. Around the corner, you see that same shaking, shivering light—like magic reflecting off of water. When you turn the corner, you see THE INNER CHAMBER:
A wide, oval-shaped room. In the center of the room, twenty feet tall, is the statue of a four armed, shark-tailed, gold-plated woman with long fangs. Some kind of rune is carved into the rock around the statue. And standing in a circle around the rune are ALL THE POSSESSED MINERS. 16 of them. Their eyes glow blue. Each of them has a vessel of water at their feet—cups, bowls, waterskins. They chant with one voice, in the same ancient language. The miners don’t appear to notice your entry.
As the PCs enter the room, the miners summon a water elemental. Their voices reach a crescendo as you enter the room, and the water from their vessels streams out and into the air. It forms a ball hovering in the air—and then seems to notice you, and turns into a wave, crashing down against you. Roll for initiative!
The PCs must fight the elemental (MM p. 125). The miners don’t join the fight; they just keep chanting. When they kill it…
The body of the water elemental, previously animated by magic, suddenly loses all form and falls to the ground in a wave. You notice the water drip into the carvings around the statue. Nothing happens for a moment. All the miners become quiet, but their eyes still glow. And then…the golden statue CRACKS. A voice rings out, and you can understand it as you feel an ancient consciousness enter the room. “ABYSSALA HAS RISEN.” The golden plate from the statue falls to the ground, revealing a shriveled mummy; but the water from the elemental surrounds her, like armor, as she steps off the pedestal. She says:
“THE WATERS SHALL FLOW, AND THE DEEP DARK SHALL RETURN. ALL THE WORLD SHALL AGAIN BE DROWNED, AND WE SHALL REIGN.”
They’ve awoken an ancient, prehistoric god! It’s time to fight Abyssala. She has the stats of an Aboleth (MM p. 13).
Don’t forget about legendary actions (can be taken after anyone’s turn, 3/round, refresh with her turn) and lair actions (the lair has an initiative of 20, can’t do the same one twice)!
Her version of psychic drain is her literally eating a miner and gaining HP.
One of her lair actions is activating a portal to the Elemental Plane of Water. This will make the chamber begin to flood.
Flood rules: The water rises one foot per round. At 2 feet, it becomes Difficult Terrain (can only move at half speed). Halflings are about 3 feet tall, Humans 5-6. When it reaches their head they have to swim or climb on something. Swimming is half speed unless they have an ability. When the water gets so high they can’t stand, they have to make a DC 10 Dex check every round. Succeeding keeps them above water. Failure means they went under water. After 3 failures they receive one level of exhaustion.
Drowning rules: After 1+(CON modifier) minutes of holding your breath underwater you become unconscious, your hit points fall to 0, and you can then survive for a number of rounds equal to your Constitution modifier (minimum 1 round). After that, you begin making your death saving throws as per the standard rules. However, if you become stable there is a problem. If you are still under water you can’t remain stable. So you must start making death saving throws again. This continues until you die or you are saved in some way.
When Abyssala is finally defeated, the surviving miners are freed from the spell (they were floating on the water during the fight) and the portal closes. The water slowly drains away. Louis and Victor are reunited (unless you’re a heartless DM and Victor dies) and you can help the miners to the surface…and enjoy pillaging the treasury and getting paid in gemstones.