An inky mass, or a roiling cloud of soupy darkness that on occassion emits a tenebrous tentacle to grope about things, strike people or the like. Its voice is a soft whisper, an itching at the back of the spine, and the sound of pale stone crumbling in the dark.
The Swollen Shadow is a cthonian entity, it has always existed, though the greatest bulk of its existance has been locaked beyond the borders of the world in the shapeless regions of the nether realms. Yet there came a ray of fire and the shadow was summoned from its cold bier and drawn into the mortal world. There it found itself faced with an opportunity. If it would expend some of its power and shield a mortal place from the rays of the harsh sun, they would be grateful. Rather than slip back into the silent monotony of the nether, the Shadow agreed.
It extended its veil across the city of Chiaroscuro and battened itself upon ley lines and places of magic within its new demense. But the Shadow had made a false promise, and planned to strike and destroy the city, but failed to do so. Now it is trapped between a summoning pact, and a queen’s sorcerous vengeance. It desires to be rid of the City of Shadows, and to that end it has begun plans to bring would be heroes and adventurers to the city to destroy the native Sihls, and to break the stone that holds it.
The Shadow is an incorporeal creature, though it is served by a vast array of servants. The lieutenants in its forces are the Haints, mortals of skill who have been taken by the shadow. Beneath them are mundane shadows, forms and figures made of tenebrous stuff that are the rank and file. A pack of shadow-beasts should be a decent match for a basic party. Unlike the magic item heavy PCs, the Shadow’s greatest resource is its almost endless existance, cunning, and ability to flee a situation.
The Swollen Shadow is ancient, and every bit as wicked as every vampire lord, mummy, or midnight monster Hollywood ever cranked out. It is also patient and cunning, willing to let others do the work for it. While the Haints and Shadow-beasts hack and kill one another, the Swollen Shadow sits securely in its broken hall, watching and maneuvering its pawns in its game of power and freedom.