These lands are lost to us. The dark rules here.The abyss are lands conquered by the dark, far away from light. They have drowned in physical dark and turned into a blackened, alien world, home to things that could live nowhere else or tolerate even the faintest light. Most of the Abyssal plains are far away from human lands, away from where the still shattered sun sheds feeble light. Everything that once lived there has died, and been replaced by things spawned and crafted from the whatever hive-mind that controls the darkness.
Slowly, the abyss has begun to change the world it now inhabits. Fungal spires raise towards the darkened skies and spew hazy clouds that dim the light and buzz with a thousand voices. The ground has been shorn down to the bedrock and rebuilt, a mix of cancerous swells and sleek, curved structures not too that jut from the earth like a ribcage. Great halls of carapace-like domes rise and fall again into the dark that created it, turning back to rot only to rise again. Tendrils that look like bone crawl like vines and cover the ground for miles.