The Penumbra

Beneath the vibrant life and hustle of Ro'Kroya, nestled deep within the womb of the planet, exists a parallel reality, a dark reflection known as the Penumbra. A realm cloaked in eternal twilight, where the sun is but a distant memory, and the concept of life itself is redefined under a necrotic sun. For here, in this realm of shadows, what is born of the light must succumb to the inky darkness.
The Penumbra's roots stretch far into Ro'Kroya's past, to the age when the elves first stumbled upon the mystical gateways buried within the caves and caverns. Drawn to the enthralling allure of the unknown, they braved the abyss, stepping into the shadow realm. Little did they realize the price of their curiosity. The necrotic energy of the Penumbra seeped into their beings, tarnishing their essence and spawning the first Drow, beings of shadow and mystery. Soon, Dwarves and Gnomes too fell under the Penumbra's influence, morphing into the stone-hardened Duergar and the elusive Svirfneblin.
The gateway to the Penumbra is capricious, shifting with the whims of the seasons. The Drow and other children of the Penumbra can track the portal's elusive paths, their beings attuned to the shadows. The surface dwellers who accidentally venture into the realm are quickly silenced, their tales swallowed by the darkness. Yet, some brave, or perhaps foolhardy souls actively seek out the gateways, their mission to seal them before the corruption of the Penumbra bleeds into Ro'Kroya.
The Penumbra is not devoid of power; in fact, it teems with a chilling energy that attracts ancient entities. Namirooz, the ancient elemental entity who once called the Penumbra home, now ascended to lesser deity status, and the Weaver of Lies, who continues its timeless battle for dominance over the shadow realm. These patrons have found in the Penumbra a fertile ground for their machinations, bestowing their dark gifts to the warlocks willing to accept their patronage.
But the creatures of the Penumbra are not designed for the light. The radiant sun of Ro'Kroya acts as a bane to their existence. Over time, the daylight chips away at their shadowy forms, causing them to weaken and ultimately perish. The sycophants, Drow, and Duergar, however, have adapted to this harsh reality, somehow managing to sustain themselves despite the sun's curse. Hence, the portals to the Penumbra are often discovered in the gloomy depths of caves or sprawling labyrinths that shield them from the lethal daylight.
The Penumbra is a realm of contradictions, a realm of shadows and secrets that thrives beneath Ro'Kroya's surface. It is a constant reminder of the universe's dual nature, a testament to the interplay of light and dark that dictates the rhythm of existence. Even as Ro'Kroya basks in the light, the Penumbra lingers, waiting in the shadows, whispering tales of the unknown to those daring enough to listen.