Out With the Old
Tytherion’s sky has no sun, no moon, no stars, only a yawning gulf of impenetrable blackness, only rarely broken up by stormclouds or volcanic smoke, ever so faintly reflecting dim light from magma and fires below. When lightning flashes in Tytherion, it is dramatic and blinding. The land itself is a blasted expanse of black volcanic rock, composed of mountains, mesas, and rock ravines. Rivers of magma pour constantly out of the craters and run in rivers of boiling rock through obsidian-lined valleys, providing the only natural illumination Tytherion enjoys. The rest of of the plane languishes in utter darkness, save for where its inhabitants build fires. It rains in Tytherion only rarely, but when it does it is usually a violent thunderstorm, sending torrents of water rushing down into the canyons. Still, this water usually boils into steam before it hits the lava pools and rivers at the bottom of the gulfs.
The mesas and plateaus of Tytherion are often covered with dead wood and parched vegetation; very little actually manages to flourish here but razorvine, and it is unclear where the dead plants originally came from. Some way that plants killed in droughts and blights on the material plane are somehow reflected here. Lava boils up through vents into the canyons, forming sluggish streams of molten rock and spewing toxic fumes into the air. In addition to its native exalted (called darksworn) and Tiamat’s Abishai minions, countless Yugoloths live here.
The surface of Tytherion is known as Samaragd, the Serpent Kingdom. Here, the serpent-god Zehir rules from the ziggurat Amun-Atl, built on an island plateau amid a city of lesser temples and monasteries all in honor of the god of darkness. The daily management of the temple city s overseen by Atlathessk, the Seneschal of the Night. Despite being an exarch of Zehir, she functions largely as his high priest, and one of her main duties is performing an endless procession of elaborate sacrifices to the serpent god, usually of intelligent beings. To reach the holy city, one must navigate a twisting labyrinth of canyons, caverns and tunnels. It is said that Zehir himself, the Great Serpent, haunts these tunnels.
The deeper canyons and caverns levels of Tytherion, particularly below ground, form the realm of Azharul, where Tiamat reigns supreme. The Queen of Dragons dwells here in her massive lair, the Caverns of Fiery Splendor, while exalted, humanoids and dragons alike, carve out their own hoards and domains. Kurtulmak the Hoard-Keeper, lesser god of kobolds, guards the massive admantine gates to the Caverns of Fiery Splendor in his obsidian tower, Draukari. In the Crawling Castle is an iron citadel that roams Azharul on thousands of clawed iron legs, and is the redoubt of Vulkur Vaal, called Vaal the Flayer, a cambion demigod with dreams of conquest.
At any given time, about half of the darksworn under Tiamat’s reign are engaged in some plot on her behalf, and the other half are left to their devices. They are frequently told to keep their activities secret even from one another, and the overall setup leads each darksworn to believe that it has been given some special confidence.
The skies of Tytherion are still contested. Tiamat’s abishai and draconic exalted are gifted with flight whereas the darksworn and other servants of Zehir are not. Thus, when the agents of any gods are found in the skies, they tend to belong to Tiamat. But Samaragd dominates the surface, and thus the dragons have no space to perch or roost. Despite the might of her servitors, Tiamat is not ready to launch a campaign against Zehir. Individual dragons who dare too much are crushed by the Midnight Serpent and his most monstrous minions.
Optional Rule: Cruel Hindrance
Tytherion is suffused with the essence selfishness and cruelty. Whenever someone in Tytherion casts a spell that has a beneficial effect to others, including a spell that restores hit points or removes a condition, the caster must make a DC 10 Charisma save. On a success, the spell is cast normally. On a failure the spell slot is expended and the action is used but the spell has no effect.
Optional Rule: Toxic Fumes:
Anyone out of doors in Tytherion must make a DC 10 Constitution saving throw each turn or suffer the poisoned condition until it breathes clean air. A creature that has resistance or immunity to poison damage automatically succeeds on this saving throw, as does any creature who does not need to breathe.
Each day a creature spends in Tytherion, it must make a DC 15 Constitution saving throw or gain a level of exhaustion. When such a creature completes an extended rest, it must repeat this saving throw in order to remove that level of exhaustion. A creature that has resistance or immunity to poison damage or the poisoned condition automatically succeeds on this saving throw, as does any creature who does not need to breathe.
The Scales, the Arhipelago and Outsiders of Tytherion
The Scales are bare, rocky islands suspended in the color sea of Tytherion. Zehir is indifferent to the outsiders who appear here; since they cannot join his realm or assist him in any meaningful way, he doesn’t spare them much thought. Many outsiders pledged to Zehir make extraordinary efforts to win Zehir’s attention, but the Midnight Serpent rarely takes notice. Often Zehir’s darksworn emerge from the plane to prey on these unfortunates for sport or personal profit. Tiamat is more hostile to outsiders; she sees them as failures, unworthy of her blessing. Dragons and draconic minions hunt the astral skies above the islands, carrying out their Queen’s will by dispatching these disgraces.
For this reason, those outsiders who remain on the Scales dwell in tunnels and dens within the islands, rather than on the surface. Many of the outsiders found here, such as kobolds, are relatively well-adapted to such living, save for the part where their gods are now trying to kill them. Portals often link these tunnels, so an outsider could disappear into one island and emerge on another. The Scales are ruled by little other than might and charisma, and the constant persecution makes them especially hostile to strangers.