THE PYRAMID, THE PRIESTESS, AND THE PIT-FIEND

The Pyramid

Nearly eighty feet high and at least as broad at the base, it dominates the small city of single-storey buildings. Crude granite blocks make up its angled walls, tapering to the apex in three distinct tiers. The temple at the top is open to the elements, and consists of four braziers around a square hole: a vertical shaft leading into the bowels of the pyramid.

The High Priestess

Nira is young. She assumed the post following the ritual suicide of her predecessor, Mirdok, who threw himself into the pit. Since this happened her dreams have all been nightmares, and always of the same thing: a hunger that cannot be sated, a gaping maw threatening to swallow the entire world, a crushing despair that has bled into her waking life.

Nira leads the acolytes and through them controls the city. She alone now realises the horrible truth: her entire culture exists in order that the Pit-Fiend be fed, else it might swallow the sun and stars temselves.

The Pit-Fiend

Fat, bloated, and mostly blind, the fiend is an enormous sack of acid stuck at the bottom of a dark hole. It wails to itself, its tiny multi-brains dimly aware that its biological imperative will never be fulfilled. It hungers... because that is all it has ever done.

The ancients brought it here: the larval stage of some long-extinct monstrosity, they stuck it in a hole and built a pyramid on top. They fed it the waste of their civilisation, harvesting its excreta to fertilise their crops.

By the time the ancients fled the Pit-Fiend had grown to gargantuan proportions. It could not move and—no longer being fed—it fell into hibernation. It slumbered for many centuries. When humans arrived at the pyramid it awoke... its fractured psyche reached out desperate in its yearning.

It found a vessel receptive to its pain, but it could only speak the language of hunger.

The cult grew around the pit, with each successive priest searching for a hidden meaning to their nightmares. The tomes of the ancients have revealed esoteric knowledge and brought them great power, but none have yet solved the riddle of how to sate the beast and quell the horrible visions. Instead, they feed it a steady stream of the sick, the criminal, the elderly and the broken... assuring their congregation that this has enabled their tiny city to prosper.

In Game

The pyramid cult can be dropped into any small reasonably isolated city.

Nira is a 5th level priestess (treat as magic-user, draws from cleric spell list). Additionally, her connection to the fiend enables her to cast charm person three times a day. She avoids combat at all cost, but truly believes that the existence of the entire universe is in jeopardy if anything happens to her cult. She is the sole arbiter of all legal disputes in the city, judging who is to be fed to the pit.

Nira is merciless, but only because [she believes that] the fate of the universe depends on a steady stream of mortals to the pit. Prisoners are kept in cells within the pyramid, access to which is obtained through guarded entrances at the base of each face.

The fiend is immobile and has no attacks. It is literally a huge stomach, full of acid. Characters falling in receive 3d6 hp of lethal acid damage each round, as do their equipment and magic items. The fiend has 100 hp, is immune to acid damage and resistant to all other forms of wounding. It can only be harmed from the inside... unless characters burrow underground and attack its fleshy carapace (no AC). If it receive five points of damage or more a spray of corrosive acid is released, inflicting d4 damage on all creatures within 5'. It regenerates d4 HP a round. Treat it as a 20 HD monster.

If Nira is slain, the fiend will reach out to the nearest character with a wisdom of 12 or more. The character must save vs charm or experience the creature’s insatiable hunger, interpreting it as its desire to eat the universe. The character immediately assumes the role of high priest. If a PC, they become an NPC under the DM’s control. They escape the creature’s nightmare visions if they travel more than 300 feet from the pyramid, and may be returned to the player. Successful saves incur 2d4 psychic damage against charisma/wisdom/whatever mental stat your OSR adjacent system uses!

NOTE (added 2022.06.15)

For clarity: the pit fiend is not going to eat the universe... that's just how powerful it's millennia-long hunger feels to fragile human brains. If left without a stream of sacrifices, it will slowly fall into a state of suspended animation... until a suitable candidate arrives to act as its next high priest.