Hellspire Citadel Settlement in Kelbonnar | World Anvil

Hellspire Citadel

Set high on a rocky promontory, overlooking the broiling expanse of the Lava Sea in the Deep Underdark, Hellspire Citadel is a remote bastion that has been home to many malign creatures and organisations in its long and murky history. Though much of its structure has fallen into disrepair, it is still a formidable stronghold, and there are many secrets and relics stored within its ancient archives and library, protected from the ravages of time by magic emanating from the Abyss.  


    When it was first constructed, the Hellspire Citadel was designed to be the headquarters and stronghold of the cult dedicated to the Demon lord Graz’zt from which they could spread the influence of their lord across the Material Plane and perhaps even establish a way of bringing his armies across from the Abyss to try and subjugate the mortal races and realms.   For many centuries, the citadel fulfilled that exact function, its position allowing it to remain undetected and its residents to operate in utmost secrecy. However, eventually, inevitably perhaps, news of the citadel’s existence spread to the ears of the Divines of Kelbonnar, who not wanting to see their work be undone by the seduction and intrigue of Graz’zt, sent their armies of Celestials and mortal followers deep into the Underdark to lay siege to the stronghold. Eventually, after many years of fighting, Hellspire Citadel fell, though at great cost to the Deities’ forces.   However, despite their victory, the Divines were unable to break the wards placed on the most secretive and dangerous places within the citadel, which were protected by power emanating from Graz’zt himself. They ordered their forces to sack as much of the fortress as they were able and they reasoned that with the destruction of the majority of the Cult of Graz’zt and its dangerous and near inaccessible location, Hellspire Citadel and its dark secrets would remain lost and forgotten at the edge of the world.   For over a millennia, the gamble of the Divines proved to be correct and the parts of Hellspire Citadel, not held together by the will of Graz’zt fell into ruin and disrepair. In recent times, however, the fortress has been reoccupied by the Covenant of the Deep, who stumbled upon its location purely by accident as they sort a place from which they could move against the established powers of the Underdark. Once more this means that as well as the fortress’ formidable defences, the dangerous secrets and lore it contains are at the disposal of its new residents, should they choose to be allured by them.   

The Demonological Archive, Library & Collection

  At the heart of the Hellspire Citadel is the Demonological Archive, Library and Collection, a trove of artefacts, records and tomes of lore and magic that were collected by the The Cult of Graz’zt during their residency there, all of which are linked to the knowledge and study of Demons and the Abyss. Originally, it was in this horde of objects and knowledge that they hoped to find the key to allowing more than a token handful of the Demons loyal to Graz’zt onto the Material Plane, from whence they could cause untold havoc.   To aid them in their quest, Graz’zt himself found away to project a mote of his power onto the Material Plane, to ensure that the collection was protected and preserved for time immemorial. It was this protection that stopped the Divines from being able to destroy the archive and it is said that access will be barred to the space to anyone who tries to enter it wishing to do it harm. Those who enter with the intent to use the material contained within, or a mind that is open to more than mere destruction would be allowed to enter by the will of Graz’zt, so that they can examine what lies within and put themselves at risk of being charmed or dominated by him.


Hellspire Citadel cuts a very stark picture in the landscape of the Deep Underdark, its black stones, towering high above anything else around it, standing out against the backdrop of the Lava Sea, with the light thrown off from the molten waves giving the whole structure a sense of constant movement.   In form, the structure is centred around a large keep, the citadel itself, which is surrounded on all sides by a large curtain wall, which also encloses and internal courtyard. Though at first glance the citadel looks like a primarily military installation, it was actually well appointed with comfortable apartments and rooms on its upper floors, though it does also have a large barracks area and space for the numerous servants who kept the structure going in its prime.   Beneath the ground, in the most secure sections of the structure are numerous chambers and passages, including an extensive dungeon complex, holding pens for wild creatures or particularly dangerous and malign entities, laboratory and research space and most secure of all, the Demonological Archive and Library.   After many years of neglect, much of the external fabric of the citadel has fallen into disrepair, with part of the curtain wall having even collapsed into the Lava Sea below, however, since the structure was taken over by the Covenant of the Deep work has begun to bring the structure back up to a passing reflection of its former glory.  

Connection to the outside World

  To say that travelling to the Hellspire Citadel via conventional methods is complex, would be to put it mildly. It’s position in the Deep Underdark means that travellers must pass through the long and complex network of tunnels and caverns of the Upper and Middle Underdark to reach it from the surface and then traverse the wastes of the Deep Underdark and avoid the rivers and tides of the Lava Sea to reach it. Navigating a way there is near impossible without a guide or a substantial amount of luck, and as the Deep Underdark is seldom frequented by most of the Underdark's denizens native to the Upper and Middle levels, such guides are few and far between.   The Citadel’s inaccessibility is no accident, its positioning is a deliberate part of its defences, but the original builders of the structure ensured that they would be able to access areas beyond their walls, in the Underdark, the surface of the Material Plane and any other plane of existence, through a complex system of portal gates which opened up directly into a room within the citadel known as the Gallery of Doors.


The citadel is set on a large rocky promontory that juts out into the molten waves of the Lava Sea, providing it with a panoramic view over the ashen wasteland and lava fields that makes up most of the Deep Underdark. The citadel is located far from the tunnels and other entrances that connect the Deep and the Middle Underdark, and its seclusion, away from prying eyes, the naturally flat top of the outcrop is set upon, as well as the relatively easy access to hard volcanic stone suitable for building, make it an ideal location for a fortress at the extremes of the Material Plane.   The height of the promontory that the citadel is set upon, along with the fact that bedrock, rather than a pocket of lava is set beneath it, means that as well as the structure on its exterior, the promontory itself is littered with chambers and tunnels that have been carved through the rock, including the extensive halls and passages of the infamous Demonological Archive housed in Hellspire.
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Cover image: by Chris Pyrah


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