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Beyond the Familiar

Dark Dimension Overview
Generic article | Oct 2, 2025

The Dark Dimension is inherently formless, and its splinters cannot be reliably mapped. Some splinters are terminal and others, coterminous. Amid the interminable wretchedness, 10 splinters have accreted as nexi of power. The denizens described here reside outside those 10 splinters but are nonetheless key players in the Dark theater.

Visual Interest Board

   

Asmodeus

Epithets

The Unbound King, The Unbound Sovereign, The Lord Below, The Archfiend, King of Darkness, The King of Order, Lord of the Infernal Dominion

Associated Splinter

Nessus, Thanatos

Stat Block

Please do not try to take Asmodeus in a fight

 

Asmodeus was not born as a ruler, though he has been one for so long that generations of devils have lived and died knowing only him as the Unbound Sovereign. Like the lowest Lemure, he rose through the ranks, suffering and surviving in the endless struggle for existence. During his lifetime, he cultivated many skill sets - conqueror, statesman, strategist. He sought something greater than personal glory: a perfect social order encompassing the Evaran omniverse.

To achieve his lofty goals would require power and control. It is said that he learned these principles from the gods - exploiting religious dogma to keep his subjects in line. He wrote a “Holy Text”, a volume known as the Asmodean Articles. The mortal edition is an abridged, 1000-page version of his doctrine. He has also written thousands of supplementary volumes and apocrypha. His Archdevils each choose a name drawn from his holy writ. These usually translate from Infernal into other languages as entire phrases, such as ‘Reach Heaven Through Violence’ or ‘Disease Equalizes Lesser and Greater Men’. Fascinated by divinity, he has gone so far as to consume the corpse of a dead god and of failed gods.

Asmodeus maintains his authority through a combination of religious hegemony, political intrigue, and raw power. All the archdevils of the Dark Dimension owe him their status. The creatures of his personal retinue owe him their very existences. Asmodeus artfully encourages infighting among his archdevils. By playing factions against one another, he prevents any single one from gaining too much power. Fear and loyalty serve him well, but his ultimate weapon is the Nessul Seed: A fragment of his own heart that can be planted within the hearts of others.

The Seed is a dark, parasitic force that allows him to subtly manipulate the fears of the host, ensuring that they remain loyal to him, even as they fight for their own agendas. Dissidence is quietly crushed through this insidious influence. Despite their efficiency, he uses these Seeds sparingly for two reasons. First, because he prefers a diverse portfolio of power so that his dominion lacks a single point of potential failure. Second, he prefers that his subjects submit to his diabolical rule of their own free will.

   

Mephistopheles

Epithets

Seneschal of the Unbound King, His Seneschal, the Crimson Son, Merchant of Souls, All That You Want is Just Beyond All That You Fear

Associated Splinter

Cania

Stat Block

Mephistopheles, Merchant of Souls  

Mephistopheles is thought to be one of the oldest archdevils in existence. Humanoid, dark-haired, and crimson-skinned, Mephistopheles’ muscular frame is clad in robes of monarchs who lost empires and more to his cunning. He stands 9 feet tall and has three sets of wings: one of black feathers, one red and dragon-like, and one of perpetually burning bone.

This ancient archdevil holds one of the most dangerous and demanding positions in the infernal hierarchy: Seneschal of Asmodeus. His duties blend administrative power, arcane oversight, and infernal diplomacy. He is responsible for coordinating the bureaucratic machinery of devilkind, handling diplomatic negotiations with non-devils, and personally appearing to bargain with high-value souls on Asmodeus’s behalf.

He is not loud; he is not brutal. He is precise, chilling, and terrifyingly efficient. He also has a disarming sense of humor and irony. In his dealings with mortals, his style is characterized by extreme subtlety. Rather than try to deceive his targets, seeks to make them a logical, compelling offer. His favorite marks are those who bury their fears beneath facts and logic.

As Seneschal to the Unbound King, his duties require him to preside over Nessus and travel throughout the Dark Dimension. His personal realm and seat of power is Cania. His splinter defies natural laws: fire burns cold, time folds in on itself, and a sharp idea can wound the body like a physical blade. His city, Mephistar, is at the apex of an impossible spire of obsidian and cursed ice. Fractal cathedrals of black frost, infinite mirror-halls of frozen truth, and laboratories built into the nerves of ancient creatures spread across the frozen realm below.

He does not entertain visitors in his splinter, and those who do come would be killed in moments without protection from extreme cold. Here and there, tucked away in Cania’s terrible environment stand long-isolated citadels occupied by sages and spellcasters toiling away at seemingly forgotten endeavors. The supervisors of these projects might have achieved incredible results that they patiently wait to share with Mephistopheles the next time their Lord directs his attention their way.

   

Muunsin

Epithets

the Gatewarden, Keeper of the Lost, Dark Traveler

Associated Splinter

None/All

Stat Block

Muunsin, the Gatewarden  

A mortal can be a gatewarden, but Muunsin is the gatewarden. They are a mystery even among the lords of the Dark Dimension: a being rumored to come from beyond Acroamatica who serves no master.

Since their arrival, they installed themself as the doorwarden of the Dark Dimension, assessing the nature of extraplanar portals breaching the plane or between splinters and closing ones that they deem harmful to The Balance. All but the newest and lowliest creatures of the Dark Dimension know of the Gatewarden and value their continued existence enough to leave them alone.

Muunsin’s form is a mass of tentacles, arranged into a roughly humanoid shape. Their body is cloaked in a shabby, grey hooded mantle, and they rarely show more than a pseudopod clutching their cruel staff. They stand an unassuming 4 feet tall.

   

Zariel

Epithets

Duchess of the Shattered Sky, Hand of the Unbound King, Reach Heaven Through Violence

Associated Splinter

Seraphage

Stat Block

As Zariel (MPMM p 280)
with the following changes:

Hear Name. Zariel hears her name when spoken, regardless of distance or planar boundaries. If a creature speaks her name twice in the same breath, she learns the creature's name. If a creature speaks her name three times in the same breath, Zariel learns the creature’s name and precise location. Unless the speaker succeeds on a Charisma saving throw (DC 26) Zariel can observe through the speaker's senses for up to 666 rounds (1 hour and 6 minutes).

Hear Plea. If a creature has ever spoken Zariel's name, she hears any of its prayers for guidance directed to The Grey Maiden, Erela. Once per day, she can answer a creature's prayer for divine guidance, imitating the effects of the Divination spell. Her answers are truthful, but always emphasize an outcome favorable to her.

 

The following Regional Effect options replace the base Regional Effects:

  • Haunting Echoes. The area within 9 miles of the lair is filled with the echoes of every desperate prayer Zariel has heard.
  • Decaying Radiance. Once every 60 feet within 1 mile of the lair, 10-foot-high gouts of arcane energy rise from the ground. Any creature or object that touches the energy takes 3 (1d6) damage, though it can take this damage no more than once per round. It the total damage rolled is odd, then the damage type is necrotic. If the total damage rolled is even, then the damage type is radiant.
  • Frozen Aurora. The area within 2 miles of the lair, but no closer than 500 feet, is filled ash and the phantasmagoric undulations of an aurora, which causes the area to be heavily obscured. These effects can't be cleared away.
 

Zariel was once a divine servant to The Grey Maiden, Erela. She believed in the holy cause, shepherding mortals through times of transition. Then came the Age of Conflict. Millennia of struggle weakened Zariel’s faith until she was exhausted and embittered from fighting the Gods’ war. She believed she could do more good as the gods’ equal, and after the war ended, she wanted Ascension as a reward for her dedicated service. The First God proclaimed his Commandments, and she was denied her wish. Zariel had nothing: no faith, no hope, and no choice but to continue the duties chosen for her by the Grey Maiden. In this role, while navigating the boundary of good and evil, she first encountered Asmodeus. He asked her a question upon their introduction.

As a result of that question, Zariel took the first step on a path that led to her own boundary: serve or leave. Asmodeus offered her a new start with power, position, and a contract in exchange for her proximity to the Divine Dimension, knowledge, and prowess. If he achieves true divinity, she will rise with him. She serves as Asmodeus’s adjutant in Nessus, advising him on all military and spiritual matters. Zariel keeps the originals of his entire body of religious texts and oversees their distribution to mortals and devils alike. She also enforces Asmodeus’s will, acting as his executioner in particularly in high-profile cases.

Zariel is an imposing physical presence. She stands 8 feet tall and a pair of dark wings sprout from her back. A halo of fire encircles her head, and eyes that glow white hot are set into an ashen grey face. A flail takes the place of a hand that she lost during the Age of Conflict.

Seraphage is Zariel’s personal splinter. Its skies are a frozen aurora of ash and dying light; its land is a wasteland of molten glass plains and blackened temples. Echoing hymns and twisted wails carry on the winds. Seraphage is haunted by memories of former sanctity, and every step feels like a desecration. It preys on those who fear making the wrong decision when they face a crucial choice and those whose desperate prayers for guidance are heard by the wrong ears.

 

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