Free D&D Underdark Adventure: Abbey of the Reflecting Mind

Like most burgeoning D&D fans, I read a lot of R.A. Salvatore’s Drizzt series growing up. His evocative descriptions of the alien environments composing the Underdark and its many inhabitants stuck with me long after I finished the series at that point. I like any adventures that take place within the bowels of the earth, as it is frankly a narratively-ripe location for players and DMs to explore. That’s why for this week’s Side Quest we’re going down, down underground to visit an abbey inhabited by a plethora of lost souls and the undead creature keeping them there. I’m happy to present our free D&D Underdark Adventure: Abbey of the Reflecting Mind! 

For those of you who are new to our blog, Welcome! We post a monthly Side Quest, which are short, free TTRPG encounters with corresponding maps that can be easily threaded into an ongoing or one shot campaign, allowing busy DMs to throw in a random encounter at the drop of a hat. Our Adventurer Level 2 tier allows our Patrons to pick the game system, theme, and name a character or two in an upcoming Side Quest. We create a free adventure around their idea, and now everyone gets to enjoy this free spooky D&D one-shot! Plus, Patrons receive a downloadable version of all our Side Quests.

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Reference Resources Needed

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Free D&D Underdark Adventure: Abbey of the Reflecting Mind

For 5th level Adventurers


Long has the abbey of the Reflecting Mind sat beneath the world in darkness and solitude. Many lost souls of the Underdark reach the broken steps that lead to a quiet temple dedicated to personal reflection of self. The abbey’s acolytes welcome all to contemplate the nature of existence in halls filled with reflective surfaces that seemingly echo the viewer’s deepest desires. In actuality, the ruminations of these lost pilgrims grant control to an allip named Lysanthir, which in turn drives all within the abbey towards a grey, emotionless madness as they sink further into themselves. Few within the abbey recognize the danger, as the echoes seen deep within the mirrors calms bygone anguish. 

Plot Hooks

  • An ally to the party has found their way to the abbey and became ensorcelled by the inhabitants. 
  • A natural spring that feeds the abbey is known to have remarkable curative powers for an incurable disease.
  • Whispers emanate from the mirrors that draw the weak-willed towards the Underdark and the Abbey therein.

Finding the abbey

The abbey resides beneath Lake Tellanala, in the northern reaches of the world. The cool, blue waters of the lake perfectly reflect anything viewed on it, though the lake is home to a tribe of particularly ornery hill giants. Sneaking past the giants is no easy feat, though they are susceptible to bribes of food or weaponry if encountered. Near the lake is a small rocky outcropping nearly invisible to casual observers, however looking into the reflection of the lake reveals a light shining out from a cave, marking the entrance to the underground system. 

The cave winds down, deep into the bowels of the earth. Adventurers must travel for nearly a week before reaching a massive chamber filled with hanging stalactites and larger-than-usual mushrooms. In the distance sits a small stone archway resting against the cave wall, with a stairwell that leads further into the rock.

Abbey of the Reflecting Mind Overview

Free D&D underdark adventure

General Features

The interior of the abbey is constructed entirely out of mortared stone, with twelve-foot-high ceilings. Doors are made of strange mushroom planks reinforced with metal, causing them to be denser than usual wood yet oddly spongy. There are no wall decorations save for odd mirrors placed randomly throughout the structure. Floors are kept clean, despite certain rooms having collapsed in years, covering some rooms in tons of rock and rubble. Light is scarce within the halls of the abbey, though certain rooms hold small crystal orbs that contain luminescent moss that provides dim light. 

R1. Founder's statues

Three life-sized statues of a drow with arms outstretched looking towards the sky stand across from each other in this circular room. A hallway leads to the east, revealing a narrow corridor choked with dust and fallen rocks to the north. Two closed doors reside within this corridor to the east and to the south. Three drow acolytes wait within this room and greet any who enter.  

Statues. The three statues are enchanted with an aura of calm emotions that affect living creatures that enter the room. Creatures that attempt to resist this spell must succeed on a DC 14 Charisma saving throw. The spell’s effects last for an hour. Each creature that fails the save or accepts the enchantment increases Lysanthir’s HP max by 2 for as long as the spell holds. 

Acolytes. Three acolytes of the Reflecting Mind await here and offer guidance to humanoid creatures that enter the abbey. They are incapable of showing strong emotions and are not hostile, but will fight if they or the statues are attacked. The acolytes have guidance instead of light for a cantrip.

R2. Reflecting pool

The sound of soft water lapping fills the air of this roughly 25ft. by 25ft. chamber. Sections of the ceiling collapsed long ago and rubble sits in massive piles in the eastern and southern corners, nearly knocking down the nearby drow statues. In the center of the room is a rectangular reflecting pool with two drow, one duergar veteran, and two deep gnome pilgrims sitting in quiet meditation on soft pillows. Their faces appear sullen upon closer inspection. Beyond the dim light on the western wall is an engraving atop an exquisite depiction of Underdark scholars. 

Statues. The statues in this room exude an aura of calmness and cast calm emotions on living creatures within the room. Creatures that attempt to resist this spell must succeed on a DC 14 Charisma saving throw. The spell’s effects last for an hour. Each creature that fails the save or accepts the enchantment increases Lysanthir’s HP max by 2 for as long as the spell holds.

Pilgrims. Getting the attention of the pilgrims is a tough endeavor, as each one is deep in thought. Any attempt to break the calm emotions enchantment, breaking a statue, or attacking a pilgrim causes them all to fly into a rage and attack any interlopers. They have few possessions, though the duergar keeps a ruby-jeweled brooch worth 100 gold pieces. 

Engraving. The wall carving shows a group of elven theologians in deep thought as identical depictions look back at themselves from mirrors. The following phrase is carved in elvish and undercommon: “Only when we reflect upon our darkest impulses does the way forward present itself”. This passage refers to the hall of mirrors (R5) to allow the adventurers to continue further into the abbey.

R3. Private quarters

Beyond a curved hallway resides a small room filled with familiar trappings of comfort: three small stools sit around a mushroom-wood table covered with silverware and half-eaten food. Two bookshelves hold a number of empty vessels and dried food containers. Various rubbish lies in dirty heaps in the corners of the room. Two duergar acolytes currently sit at the table nursing some kind of fungus-based alcohol and mull over the past. They are incapable of showing strong emotions and are not hostile, but will fight if threatened.

R4. Intersection

Two dim lights flicker softly in this small room. Two doors are visible: one to the north and one to the west. Both doors are unlocked. Opening the western door reveals a shallow chamber with a floor to ceiling mirror directly facing the doorway. Anyone peering deeply into the mirror spot swirling shadows drifting off of their reflection. 

Wall mirror. The allip Lysanthir sees and travels through this mirror, and his followers speak to him through it. The mirror takes no damage if attacked.

Water Cell Watermark
R5. Hall of mirrors

A brief sense of vertigo washes over the adventures as they set foot into this room. Mirrors cover the walls in this space, reflecting light across multiple surfaces, nearly blinding anyone in the room. Only when the lights are doused do the reflections appear on the surfaces despite the gloom.

Shadow demons. Two to three Shadow demons lurk on the other side of the mirrored surfaces and take on the appearances of anyone who enters. They perfectly mimic all actions, yet their faces hint at an unworldly evil. They step out of the mirror wall once a character “reflects” on their darkest impulse (allow for some roleplaying) and attack. Once they are slain, a secret door on the western wall opens.

R6. Shrine

Beyond the hall of mirrors lies a 15ft. by 35ft. chamber. Four statues stand across from each other in the center, while a half circle alcove holds a plinth topped with a swirling crystal ball. A dark-robed duergar priest watches the swirling patterns intently. Before the adventurers can interrupt the priest, a swirling black miasma forms in the center of the room as Lysanthir materializes, floating above the floor. The apparition offers promises of dark secrets and a release from earthly stresses if they “only look inward”. If attacked, the priest defends Lysanthir. 

Lysanthir. The apparition appears as an elderly male elf bathed in swirling shadows that obscure his lower torso. The allip speaks Common, Elvish, and Undercommon. Lysanthir has an additional 22 hit points as long as the original inhabitants of the abbey are still under the calm emotions spell. 

Statues. The four statues are enchanted with an aura of calm emotions that affect living creatures that enter the room. Creatures that attempt to resist this spell must succeed on a DC 14 Charisma saving throw. The spell’s effects last for an hour. Each creature that fails the save or accepts the enchantment increases Lysanthir’s HP max by 2 for as long as the spell holds.

Secret door. Opening the door at the end of the hallway reveals a floor-to-ceiling length mirror that shows the door opposite it in room R4. Creatures may pass through as if the mirror and wall were not there, though the route is one way only. 

Treasure. The swirling orb on the plinth is a crystal ball used by Lysanthir to watch the inhabitants of the abbey as well as others in distant lands.

R7. Stairwell

Around the corner, past a collapsed hallway lies a small chamber holding a stairwell that leads further down beneath the abbey. A single dim light provides scant illumination. 

Lower floors. The lower floors of the abbey may contain many things. It’s up to the Dungeon Master to decide if the stairs lead to a single room or continue on to further adventure. 

  • If a single treasure room is needed, it contains the following items: 400 cp, 9000 sp, 2700 gp, 90 pp, a painted glass ring (25 gp), a pair of pewter bracers (25 gp), an iron mask (25 gp), a bag of holding, and a robe of useful items (including 8 additional patches).

Wrap up

That’s all for the Abbey of the Reflecting Mind! I hope you all enjoyed this free D&D Underdark adventure and are able to work it into a larger campaign. Mayhaps Lysanthir is a pawn of a greater monster, or they hold some secret to unlock even greater treasure (or danger)! We would love to know what you and your party thought of our Side Quest, so please drop a comment here on the blog, on Twitter, Facebook, Instagram, or Discord to let us know how it went! If you’d like access to more maps and content, including downloadable PDFs of our adventures, check out our Patreon. We’re able to do what we do because of all our amazing Patrons!

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