The Library of the Bat God, a Saturday Morning Dungeon for 3rd Level D&D Adventurers
“Forbidden Lore” by Clyde Caldwell, ©1992, 2025 Wizards of the Coast, Inc.
I was recently forwarded an article that so reeked of a dungeon crawl that I just had to put pen to paper after reading it. A good while back, the Smithsonian covered a Portuguese library from antiquity that has cultivated a polite bat infestation to deal with the moths who would otherwise terrorize the collections. The sheer gothic patina hinted at here had my mind racing, already constructing bat-themed puzzles and more eldritch reasons for such a symbiotic relationship. I’ve always thought of libraries as these cavernous, dungeon-like environments, and I’ll take any chance I get to set a one-shot in between the bookcases!
I’ve recently been working with some of my fellow DMs here in NYC on puzzles that can be solved without Investigation checks, as well as dungeons that hint at a greater story, and I wanted to test my chops on both those fronts. Using D&D 2024 as my source code, I’ve created the following little delve for 3rd Level PCs that could just as easily be rerto-fitted and used for an OSR system such as Shadowdark or Mork Borg. Enjoy this little foray into the grim subbasement of a library near you, and remember, sometimes the truth really can be stranger than fiction…
Adventure Background
Definitely the bookplate of an above board library.
A cabal of occult-obsessed literati called the Historiaters are said to have excavated the ancient resting place of a lesser-known deity from a long-extinct cult. The deity was the bat devil known as Candleflame. Once a young scholar who traveled into the underworld to rescue his deceased lover, his soul was twisted into a hateful being with immense power and a hunger for human blood. Candleflame terrorized this countryside for some time, coming to be worshipped by the locals, only for a great disaster to leave many of the devil’s new worshippers dead.
When the Historiateters uncovered Candleflame’s temple, they bound the dormant devil to a curse, forcing him to protect their collection without being able to return to the Abyss from whence he came. They built their library around the temple, but it is said they were killed when the bat devil snuck a curse of his own into the ink of the library’s scribes. The curse placed upon the devil can only be broken if a human is sacrificed intentionally to the devil in the library. If one were able to defeat Candleflame, they may well uncover untold magical secrets from an age long gone…
Setup & Hooks
Characters may stumble upon the Library of the Bat God while exploring old ruins or while searching through the undercity of a major settlement, coming across a trapdoor leading to Area 1. Alternatively, the characters may be tasked with retrieving the valuable texts guarded within, or given an extermination job after a spree of bat-related killings. However the characters come across the library, any characters who have spent time in the area will no doubt have heard the rumors of its existence.
Map of the Library of the Bat God, created using Dungeon Scrawl
Area 1, Key Room
As the PCs enter, read:
“As you inch down the stairs, cobwebs threaten to strangle the last of the light. Scraps of parchment litter the steps. For a moment, you see shapes in the small room, shifting in the gloom as if in sync with your motions. They are your reflections, dancing on the brass surfaces of huge locks covering the entire back wall of the basement. Each lock is decorated with filigree bat wings. Hanging motionless above, a dozen or more misshapen iron keys dangle like the creatures that are said to haunt this forgotten sepulcher.”
There are five locks, each with an Abyssal numeral on it. The locks are numbered in Abyssal 1-5. Above are 8 keys, lettered in Abyssal with “A,” “B,” “C,” “D,” “E,” “F,” “G,” and “H.” Each key unlocks the lock that corresponds to its placement in alphabetical order (i.e., the “A” key unlocks the “1” lock). The “F,” “G,” and “H” keys are there to confuse treasure hunters. Once the first 5 keys have been placed in the corresponding 5 locks, the secret door to Area 2 opens.
Area 2, Library Entrance
Bookshelves 30’ tall line the two hallways. Investigative players may notice the hardened bat guano on some of the shelf surfaces, as well as the skeletons of small rodents and dessicated insect nests. Searching the bookshelves requires a DC 13 Investigation check to find a legible manuscript, inside which is a rumor of your choice. There is a well-hidden (DC 17 to find) secret door leading to Area 10 at the corner of the hallway, which can be opened by unlatching the bookcase and folding it in on itself. The door to the south leads to Area 3, the door to the east leads to Area 4.
Area 3, Librarian’s Office
The walls in this small study are lined with bookshelves, surrounding a small desk. When the PCs enter, x3 Animated Books fly up from the desk and attack. Use Animated Broom statblock from Monster Manual, pg. 16. The books on the shelf are mostly historical tomes, but with a DC 15 Investigation check, a character can discover the Epic of Candleflame. The book details a hero's journey as he traverses the underworld and is transformed into a lesser deity in the shape of a bat. Mortals then enslave the deity, and it loses its influence in a tragic fall.
On the desk, there is a bag of “Bat Biscuits,” treats that can be used to placate bats. There is also a scroll that reads, “Where the chapters diverge, dogear the case.” This clue corresponds to the secret door in Area 2.
The library seems more alive with every step you take…
Area 4, Reading Room
The high-ceilinged room houses 6 bookcases, each filled with corrupted tomes of magic. There are 2 skeletons in robes, dead in the 2 chairs, each with one of these corrupted books in their lap. Reading any of these books provokes a DC 15 Charisma Saving Throw, resulting in 2d6 Psychic damage on a failed save or half as much on a success. If a Remove Curse spell is cast on these books, they become harmless and contain one of the following spells: Detect Thoughts, Arcane Lock, Enlarge/Reduce, Spider Climb. The door to the south leads to Area 5.
Area 5, Hunting Hallway
This cramped T-junction hallway is lined with empty bookshelves, many of which have become makeshift roosts for bats. Right before the door to the south, the fresh corpse of an adventurer is being picked at by x1 Swarm of Bats (Monster Manual, p. 370). The swarm will attack if a character gets within 10 ft. of the corpse. The bats can be made docile with the treats found in Area 3. The corpse is of a half-elf fighter named Roddick, and he has the following on his person: a shield, a shortsword, a dagger, and a crumpled love letter. The door to the east leads to Area 6, and the door to the south leads to Area 7.
Area 6, Museum
Four statues of ancient warriors rise out of square pedestals, surrounding a large disc covered in symbols. The disc has 8 hands that can be moved to point at different numbers on the outer ring. Numbers 1-12 are engraved on the outer ring, and the answer to the puzzle lies is in the plaques under each statue. The statues names are as follows:
“Septimus Duos”
“Trese Octos”
“Unus Decemus”
"Novemus Sextus”
If the numbers 7, 2, 3, 8, 1, 10, 9, 6 are pointed to with the hands, the disc unlocks to reveal a small chest containing a Hat of Many Spells (Dungeon Master’s Guide, pg. 266).
Paper Golem
Large Construct, Unaligned
Armor Class 14
Hit Points 85 (10d8 + 40)
Speed 30 ft.
STR 17 (+3)
DEX 16 (+3)
CON 18 (+4)
INT 3 (−4)
WIS 10 (+0)
CHA 1 (−5)
Saving Throws Dex +5, Con +6
Damage Vulnerabilities fire
Damage Resistances: bludgeoning and piercing from nonmagical attacks
Damage Immunities: poison, psychic
Condition Immunities: charmed, exhaustion, frightened, poisoned
Senses: darkvision 60 ft., passive Perception 10
Languages: Understands Common
CR 3 (700 XP; PB +2)
Traits
Immutable Form. The golem is immune to any spell or effect that would alter its form.
Magic Resistance. The golem has advantage on saving throws against spells and other magical effects.
Actions
Multiattack. The golem makes two Slam attacks.
Slam. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage.
Area 7, Guard’s Post
As the characters enter this room, read the following:
“Ink-black walls stretch over the obsidian floors of this room. Out of the darkness, two statues tower over you from either side of the chamber. They are cobbled together from pieces of destroyed manuscripts, large sculptures of folded paper and wax. The humanoid creatures wear gauntlets packed with waxen spikes. In the span of another breath, the sculpted limbs of the creatures begin to tremble as these constructs rumble to life!”
The x2 Paper Golems attack, each powered by an amethyst in its chest cavity. The door to the South East leads to Area 8, and the door to the South West leads to Area 9.
Area 8, Illusion Hall
This hallway has been enchanted with an illusion that causes the middle part of the hall to “repeat,” causing the end of the hall to look constantly far away, and the door behind them to look like it is getting further away. The door in front of them is just an illusion, and the door behind can be reached with only a few steps. The only way to end the illusion is to dispel the magic or destroy the rune at the end of the hall (visible with Truesight).
The real door around the corner of the hallway is made of a substance that can be written on and has been written on with chalk, displaying many random words, none of which seem to have unlocked the door. The word “Candleflame” unlocks the door if written there, and the door leads to Area 11.
Area 9, Hall of Portraits
Oil paintings hang on the walls of this hall, mostly of bearded wizards and warlocks. There is a landscape painting at the end of the hall as well. The landscape painting is actually an expertly painted optical illusion diorama that can be noticed with a DC 13 Perception check. Reaching in the diorama, a character can find a Figurine of Wondrous Power, Onyx Dog (Dungeon Master’s Guide, pg. 262). The door at the end of the hall leads to Area 10.
Area 10, Scriptorum
When the characters enter this room for the first time, read the following:
“The scent of fresh air pours out of the door as you enter. Thin strands of moonlight illuminate the middle of a vast scriptorum, casting pale shadows from a crack in the high ceiling. Crumbling stone walls form a high cubicle in the center, where the bodies of the scribes that once kept these quarters play host to decay. The sound of the door shutting behind you sends a ripple of sound through the crypt, heralding the first movements of the eleven skeletons rising from the ground.”
These x11 Skeletons (Monster Manual, pg. 282) attack when characters enter the area, each wearing a long robe embroidered with a large letter. Each of the skeletons carries a sickle and 2 silver pieces. The letters on the skeleton’s robes are an anagram that spells out “C-A-N-D-L-E-F-L-A-M-E” if rearranged.
There is a chest in the north end of the room that contains a Scholar’s Pack and a bronzed human skull (50 GP).
Area 11, Candleflame’s Rookerie
When the character’s enter this room, read the following:
“Shadows dance along the bronze railing of a small balcony, looking out over a cavernous stone tower filled with wooden amulets hanging from unlit torches along the walls. Looking over the railing, the smell of death wafts up from amorphous shapes at the bottom of the chamber. Majestic, membranous wings smother a hoard of strange trinkets. Rotating with predatory intent, a massive head opens two sightless eyes. Cadaverous nostrils flare in the center of the face as a mouth of moonstone teeth opens. ‘HAVE YOU COME TO RELEASE ME?’ a voice like nails on chalk calls. ‘RELEASE ME FROM THE HUNGER OF DECAY? COME QUICKLY. I GROW WEARY OF WAITING.’ The humongous bat flutters into the air and cries with piercing agony!”
“Vampire Bats” by Anson Maddocks, ©1995, 2025 Wizards of the Coast, Inc.
Candleflame uses the statblock of a Chasme (Monster Manual, pg. 69) except for the following alterations: speaks Common in addition to Abyssal, flavors the “Drone” attack as “Screech,” is a Devil instead of a Demon, and does not have access to Demonic Restoration unless its curse is lifted.
If Candleflame is bloodied, it will offer a deal. “CEASE YOUR STRUGGLING! SACRIFICE ONE OF YOUR OWN AND I MAY RETURN TO THE ABYSS, FROM WHENCE I MIGHT BESTOW YOU WITH POWER UNTHINKABLE!” The curse keeping Candleflame weak and unable to use Demonic Restoration can only be broken through human sacrifice (as in, not killed by Candleflame).
If the curse is broke, the bat god disappears as it teleports to the Abyss. The surviving characters will be tormented by terrible dreams, and over the course of 2d6 days, they will grow batlike wings out of their shoulder blades giving them a fly speed of 30 ft. as well as granting them the spells Shatter and Spider Climb to use as cantrips.
If Candleflame is killed, it will cry, “THE PATHETIC SONG OF YOUR LIFE WILL BE DROWNED IN THE ENTROPIC HARMONIES OF THE END! WEEP AS THE CANDLE’S FLAME DIES, AND THE REST IS DARKNESS!” The creature will then melt into a corrosive sludge that deals 2d8 Acid damage to whatever it touches.
The hoard in the center of the room contains the following: 200 sp, 3 Azurites (10 gp each), 2 Bloodstones (50 gp each), a gold compass with a bat engraving (25 gp), a Manual of Golems (Paper Golem, 20 days to create, 30k gp materials to create) (Dungeon Master’s Guide, pg. 277), and a cursed Cloak of the Bat (Dungeon Master’s Guide, pg. 245) that inflicts 1 Level of Exhaustion every time its magical properties are used.
One of the many trinkets in the shape of the dread lord Candleflame…
