The Mouth of the Dying God:
A Cosmic Horror One Shot for Small Groups

If you have ever wanted to run a cosmic horror one shot that drops your players inside the open mouth of a dead god drifting through the Astral Sea, this is the book. The Mouth of the Dying God is a complete 5e-compatible adventure designed for two or three players at level two or three, runnable in a single two-to-three hour evening, with no preparation required beyond reading the book once. The setting is unlike any other planar adventure on the market: the party walks across an actual tongue, climbs the inner face of an actual molar, and stands on the upper palate beneath a closing jaw. The cult that lives inside is sincere. The choice the party faces is real. There are no clean endings.

This adventure was written for the dungeon master who wants moral weight without two weeks of preparation. The plot delivers an unexpected emotional pivot at exactly the moment the party thinks they understand the job, and the climax is not a boss fight but a question your players will be talking about long after the session ends.

What Makes This Cosmic Horror One Shot Work

Most planar adventures lean on the strangeness of the setting and treat the inhabitants as monsters. The Mouth of the Dying God does the opposite. The setting is the most distinctive thing about it, but the cult inside is the heart of the book.

A Setting You Have Not Seen Before

The dead god’s body has been petrified and drifting through the Astral Sea for centuries. Now it has begun to decay. The mouth is open and large enough to hold a city. The teeth are skyscraper-sized pillars. The tongue stretches back like a continent of soft pale flesh. A fortress city — the Citadel of the Children of the Teeth — has been carved into the rear molars. The salivary gland pits at the upper palate are the cult’s ceremonial chamber. Every act of the adventure takes place inside a body part rendered at architectural scale, and the body horror is environmental rather than gross-out: the slow grinding of the closing jaw, the dust falling from above, the soft pink gum line where the teeth meet flesh.

A Cult That Is Not the Villain

The Children of the Teeth are sincere believers. They are not deceived, drugged, or coerced. They came to the body voluntarily, often after hearing recruiting sermons in port-side temples on the Material Plane. They know what the Great Communion will require of them. They have been preparing their entire adult lives. When the players meet them, they are calm, kind, and absolutely committed. The horror of the adventure is that the cult means every word.

A Moral Fork That Lands Hard

The party was hired to retrieve a missing son. The wizard who subcontracted the job did not tell them the man has been on the Astral Plane for forty years and now leads the cult. He has a wife. He has a young son. The wife wants the boy saved. The husband wants the boy taken into the gland pit with the rest of the congregation as an act of love. The party has one portal vial. It opens once and stays open for fifteen seconds. They will leave with one of three outcomes, and every outcome costs something.

What makes the fork land at the table is that nobody in the scene is acting in bad faith. The husband loves his son. He believes the rite is the highest gift a father can give. The wife loves her husband. She is going willingly into the pit herself. She believes only the child cannot consent and that consent is the heart of the rite. The wizard back home does not care what happens, only that the contract is fulfilled. The patron who hired the wizard wants his bloodline back before he dies. There is no monster in this room. There is only the choice the party has to make in fifteen seconds.

Built for Small Groups and Busy DMs

This is a Ready Adventure Series book, which means it was built specifically for tables of two or three players rather than scaled-down from a five-player module. Every encounter is calibrated for the smaller group. The Pit-Sworn boss fight in the climax has been balanced against level two characters with depleted resources, and a built-in challenge dial lets you tune the difficulty up if your party is unusually capable.

The book is genuinely zero-prep. Read it once, run it that night. The four acts are structured to keep the session within the two-to-three hour window: a fast contract briefing, a travel act with a single meaningful encounter, a confrontation with the cult leader’s wife that delivers the central revelation, and a climactic ceremony that resolves the moral fork. Read-aloud text is provided at every key beat. Skill check DCs are written out. The vial mechanic — fifteen seconds, one use — does the work of the climax’s tension without requiring you to track a complex round-by-round timer.

What Is Included

The Mouth of the Dying God contains a complete adventure across four acts with full read-aloud text throughout, six battle maps including a top-down overview of the dead god’s mouth and a side-view diagram of the rear approach to the Citadel, three custom creatures fully statted (Festerlings, Bristlestalker, and the Pit-Sworn cult lieutenants) plus standard cultist tiers for the supporting encounters, eight named NPCs with motivations and behaviour notes, four pre-generated characters at level two with full sheets and personal hooks into the contract, six campaign opening hooks for plugging the adventure into your existing game, six closing hooks for continuing the campaign past the one-shot, a player-creativity guide covering nine common ways parties depart from the expected structure, three distinct endings tied to player choice with full aftermath text, and a DM challenge dial for tables that want a harder climax. The book is sized for the standard six-by-nine paperback format.

Perfect For Tables Like Yours

Duet and trio campaigns. If you run a regular game with one or two players plus yourself, this adventure was designed for you specifically. Encounter math, NPC count, and pacing all assume a small group.

One-shot nights. If you have a free Saturday and a friend who wants to try D&D, you can read this book in the afternoon and run it that evening. The pre-generated characters mean nobody needs to spend time at the front of the session rolling stats.

DMs who want moral weight. If your players have grown tired of monster-of-the-week one-shots and want a session that ends with a long quiet pause, this delivers exactly that.

Cosmic horror fans. If you enjoy the planar weirdness of Spelljammer, the body-horror sensibility of certain Magic: The Gathering planes, or the moral sincerity of a great Studio Ghibli film, the tonal blend in this adventure will land.

Busy dungeon masters. If you have two hours to plan and a session to fill, no-prep adventures are the only kind that actually get run. This one was designed with that constraint in mind from the first sentence.

About the Ready Adventure Series

The Ready Adventure Series from Anvil N Ink Publishing is the company’s core line. Every title is a complete one-shot for two or three players, written for level two or three characters, runnable in a single evening. New titles release on a regular cadence and span the full tonal range from light comedy to cosmic horror. Browse the full catalog at anvilnink.com.

Step Into the Mouth Tonight

The Mouth of the Dying God is available in paperback for in-person play and as a PDF for digital tables. The paperback is the primary format and is built for the way most DMs actually use a book at the table — flipping back to a stat block, marking up a battle map, leaving the book open at a tilt. The PDF is the right choice for VTT campaigns and for DMs who travel light. Both formats deliver the same complete adventure, the same six battle maps, the same three custom creatures, and the same three endings.

If you have ever wanted to run a cosmic horror one shot that respects your prep time and gives your players a choice they will remember, this is your book. Open the vial. Walk into the mouth. Decide who walks out.

The Mouth of the Dying God is a complete cosmic horror one shot for 5e — small group, single session, three endings, no clean answers.