Avernus

Avernus was the first layer of the Nine Hells of Baator. The most likely beachhead for any attack by demon-kind, it was the primary battleground of the Blood War: legions of devils marched across its plains in continual readiness to repel the hordes of demon invaders that sailed the River Styx into the layer.

Geography
The layer was a charred wasteland of vast ashen plains covered in rubble and the occasional line of foothills and basalt mountains heaped with broken rocks of obsidian and quartz. The ubiquitous presence of rocks and boulders, some of which seemed to resemble tormented faces and shapes of creatures, rendered the terrain extremely treacherous and difficult to cross at any pace quicker than a fast walk.

A blood-red light suffused the very air and huge fireballs flew at random through the sky, occasionally impacting and exploding wherever they hit. There was no sun or stars in the Avernus sky. Travelers needed to get to shelter like a building or cave, lest they inevitably be struck.

As with all the lower planes, the River Styx ran through Avernus, with a number of offshoots and falls. Rivulets, lakes, and streams flowed across Avernus's plains and fed the Styx. The source of this blood was not known; devils claimed it probably came from all who had died on Avernus.

The layer's territory was also in a constant state of expansion by military conquest. The Styx, which at one point flowed at the edge of the layer, was later located at its center thanks to a relentless baatezu campaigning and conquering of gate-towns along the layer's edges.

Government
The ruler of Avernus was titled the Lord of the First. This position was held by Zariel, who had been betrayed by Bel, and then supplanted him again by the late 15 century DR. Bel, a pit fiend general from Dis, was demoted by Asmodeus and made her advisor. She resided in a soaring basalt citadel. When he ruled, Bel dwelled in his own fortress at the center of the Bronze Citadel.

History
Avernus was once ruled by then-archfiend Tiamat, who served Asmodeus faithfully. Her job was to prevent outcast devils on the layer from becoming a threat, but she performed so poorly that Asmodeus demoted her. Knowing her failure was not deliberate by reading her thoughts, Asmodeus deigned to allow Tiamat to remain in Avernus unpunished, and even gave her a chance to regain her position if she impressed him in her new role as the guardian of the main gate to Dis. This state of affairs lasted until 1346 DR when Tiamat was elevated to status of demigoddess.

Avernus was then ruled by Zariel, until she was inevitably betrayed by Bel, a pit fiend general waging the Blood War and not one of the Dark Eight. He was Lord of the First by 1372 DR. Bel's minions whispered that he kept Zariel prisoner deep within the Bronze Citadel and drained her of her hellish power, slowly turning her into a soul shell while he enhanced his might. Lacking the support of the other Lords of the Nine, bar maybe Asmodeus, Bel could advance no further, at least for the time being.

During Bel's rule, Asmodeus asked Tiamat to offer covert aid to Zariel in order to prevent Bel from becoming too powerful, in a ploy orchestrated with Bel to keep Tiamat herself in check, effectively making her a prisoner in Avernus.

Some time after the Spellplague, Asmodeus offered Tiamat the rulership of Avernus once more. However, to avoid disappointing Asmodeus again and to prevent a conflict with Bel, Tiamat refused, instead offering to be Asmodeus' champion and devouring all who opposed him.

Some time later, Bel fell out of favor with Asmodeus for his inability to successfully repel a demonic invasion of Avernus. Zariel reclaimed her title as Lord of Avernus following Bel's demotion. He was forced to serve as Zariel's advisor and remained one of her chief lieutenants, waiting for her reckless tactics to lead to a mistake, so he could claim his title back.

Before Zariel's second rule, Avernus was known to be a rich and civilized realm of cities and commerce. The Blood War reduced the entire layer to a blasted and abandoned wasteland, whose only functioning structures were military citadels to muster the devilish forces.

Upon her return to power, Zariel, still enraged from having been at Tiamat's mercy, assisted Severin Silrajin and a group of Red Wizards of Thay to free her from Avernus, if only to rid the layer of Tiamat's presence.

Notable Locations

 * The Bronze Citadel: A huge fortress-city dozens of square miles in extent and ringed by twelve heavily defended walls. It housed hundreds of thousands of lesser devil troops and war machines. It was constantly being added to in the form of new fortifications against attacks. The Lord of the First reigned from here.
 * The Pillar of Skulls: A hideous landmark of trophy-skulls of those killed in the Blood War. It reached a height of more than 1 mile (1.6 kilometers). It was very close to the entrance to the second layer, Dis.

Divine Realms

 * Draukari, the realm of the chief deity of the kobolds, Kurtulmak.
 * Peaceable Lands, the realm of Bargrivyek, the goblin god of co-operation and territory.
 * Tiamat's Lair, a tall mountain that was the prison of Tiamat in the Great Wheel cosmology. It was somehow connected to the Dragonspawn Pits of Azharul, Tiamat's main realm. A massive cave mouth near the base of the Pillar of Skulls led into Tiamat's Lair; from here, she could guard the crossing to Dis against demon attacks.

Connections
An especially high metal spire of Dis, the plane below, skewered trough the haze between layers and emerged in Avernus near the Pillar of Skulls. Its spiral stairwell let devils and petitioners cross on foot between the layers, with many falls, by chance of otherwise.

A portal to Avernus was erected in the Burial Glen of Myth Drannor by Banites loyal to the High Imperceptor of Mulmaster, but under the influence of Zhentarim agents and, by proxy, a cabal of alhoon living in the ruins. The alhoon had it erected so that the devils it spawned would prevent the local phaerimms from attacking the liches while they searched the city for magic. Although the portal was closed by the Knights of Myth Drannor, the devils it had already unleashed continued to infest the ruins until the Elven Crusade led by Seiveril Miritar.

Another portal to Avernus was erected in Dragonspear Castle by a Calishite mage after Daeros Dragonspear, the castle's builder, was tricked into sacrificing himself.

Inhabitants
Legions of devils dressed in mail stood an eternal watch on Avernus, in readiness for a sortie in the Blood War.

Devils in Avernus were known for some common sayings:
 * "Avernus welcomes all."
 * "Fires of the pit!"

Background
Avernus was an ancient name for a volcanic crater located near Cumae, Italy which the Romans believed was the entrance to the underworld.

Appearances

 * Well of Worlds
 * The Rise of Tiamat
 * Baldur's Gate: Descent into Avernus

Connections
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