Three destinations await the damned, each one suited to the soul’s alignment. Those of chaotic evil alignment tumble into the endless depths of the Abyss, home of the demons. Lawful evil souls are drawn into Hell, where they must suffer torments from the devils who dwell there. Finally, those of neutral evil alignment find themselves trapped in the horrifying realm of Gehenna, where they must face the personifications of their mortal failures.
Whole cities rise and fall at the whims of distant masters, in endless cycles that seem only to prove the inevitability of anarchy and decay. The aimless souls of mortals range from layer to layer, fearing capture from nigh-omnipotent lords eager to suck essence from their metaphysical marrow. Landscapes leach life, color, and nutrients from those who attempt to settle them, and wild beasts controlled only by hunger and lust haunt jungles infested with murderous plants and poisonous streams.
Few foreigners survive long in the Abyss. The plane seems to be designed by a bickering assembly of insane, but nonetheless brilliant, architects for the sole purpose of punishing and destroying its inhabitants.
Visitors to the Abyss must survive the trials of the Howling Threshold before descending to the lower layers. It is here the souls of the damned first appear after death and find the fate awaiting them from spending a lifetime in service to chaos and evil. The uppermost layer of the Abyss, the Howling Threshold, is a blasted plane speckled with the ruins of demonic outposts, grim castles, and old battlefields marking clashes with the devils, celestials, and other would-be invaders of this hateful place.
Hot winds blow across the pitted landscape, carrying rust-red dust tinged with the coppery taste of blood. Fires bloom in the smoke-filled skies to bathe the ground below with sickening light. The ground trembles, thunder booms, and every now and then, black rains fall from the ebony clouds drifting across the burnt dome that covers this hideous place.
Though soul forms make up the majority of the Howling Threshold’s populace, the place is rightly feared for its demonic inhabitants. Millions of demons fly its turbid skies and roam its vast plains. Most of these creatures serve no master, feasting upon souls simply because it gives them pleasure to do so. Countless demons live out near-immortal life spans with goals no more complicated than killing, eating, and fornicating.
Thousands of demon lords live in vaunted fortresses spaced irregularly through-out the layer, commanding infernal armies in their quest to corrupt the mortal world or establish themselves as princes in the lower Abyss. These beings include the diseased Ahazu the Seizer, calculating Aldinach of the Thirty-Three Terrors, desiccated Baltazo the Pitiless, and the errant lord Laraie of the Unerring Bow.
In addition to independent demon lords, unique, powerful nobles in service to demon princes roam the plains of the Howling Threshold, seeking captives for their dread masters. These beings, and the countless servitor creatures that aid them, gather huge groups of souls, prodding them toward the conduits leading to the realms below. These portals are heavily fortified for miles around and are known as Harvest Gates by demons and souls alike. Few captives thrust into these grim passages ever emerge to tell the tale of their travels.
Some Harvest Gates lead to the personal domains of demon princes such as Demogorgon or Abraxas, but just as many open to vistas of indescribable horror untamable by even the fiercest demonic lord. Certain self-described scholars in the city of Amalrehtan claim to have cataloged the known Harvest Gates, but whether or not they can be trusted, and what they charge for such information, is a matter of rank speculation.
The only significant, long-standing independent enclave offering some shelter to souls is the cyclopean city of Amalrehtan. Situated near the center of the layer, Amalrehtan sports hundreds of partially ruined towers, great bulbous domes, and mostly destroyed genetic foundries. The ancient city was built by the qlippoth—a godlike terrible breed who claimed the Abyss prior to the arrival of the demons—but was abandoned at the height of the war against the celestials.
Now, demons avoid the city and its extensive dungeons, which occasionally belch forth eons-old horrors that savage any foolish enough to let down their guards for even a moment. Because most Abyssal creatures shun it, Amalrehtan has become a haven for travelers from other planes, including the Material, and rumors tell of great marketplaces filled with transplanar lore and treasure unavailable anywhere else in the multiverse.
Nowhere is it more apparent that evil has many forms than in the lower realms of the Abyss. Some layers present alien landscapes rife with malevolent vegetation and even more harmful inhabitants. Others contain no atmosphere or air crackling with poisonous fire that consumes all who breathe it. Certain layers seem to be sentient creatures in and of themselves.
Simply choosing a gate at random and wandering to some unknown lower layer is as good a form of suicide as any available across the Outer Planes. Ironically, the safest layers are often those dominated by a particular demon prince, as these nobles must force their realms to be hospitable enough for their legions of demonic followers and soul-form chattel.