something rotten

A new hill is forming, the ground slowly stretching over what lies underneath. The grass on the hill has turned stringy and yellow-brown, yet the grass around the hill seems secure for now with small patches of yellow. Approaching the hill, there are subtle signs of taint.

• Animals refuse to approach the hill. Steeds will need persuasion to get closer, supernatural creatures are disinclined to approach without a good reason. There isn't a tangible smell as such, more of a feeling. Those rightly proud of their intuition will sense something wrong.
• The notable exception to this are carrion eaters and scavengers. Oily-black crows and feral dogs circle the hill; a sleek and well-fed rat may rush through the grass seeking to tunnel into the hill to find food.
  
• Hairline fissues sometimes form on the hill, from these cracks gust clear, foul-smelling mist to taint the air and sicken the weak and unwary. The cracks collapse as more ground is pushed out, filling quickly and too narrow for most breathing things to pass through.

Digging Deeper
Beneath the topsoil is a horrific amalgam of grey mud and blackened putrid flesh, shaped into chambers and corridors that radiate away and down like a web woven of cancerous fungus; the stench is unbearable at first but fades in time to become a bad taste in the mouth. Where the digging takes place reveals different things.

• The top of the hill opens out into a chamber with seven sloping corridors leading away from it. On the walls are frescoes of skeletal figures striking down twisted depictions of people with diseases. Those who attempt to leave the chamber without praising the one who made this place will find the skeletons able to leave their frescoes and can attack.
• Halfway down the hill there is a curving corridor, which if followed encircles the entire hill; there are entrances into chambers deeper inside the hill. What lies in those chambers will sicken and infect those who adventure inside - diseased ghouls, bubbling fonts of fouled water (the source of the sickening vapours) and icons of plague and rot.
• At the base of the hill, digging reveals shafts and sloping corridors leading to chambers strewn with flyblown-piles of waste and writhing maggots. Diseased ghouls are chained to protect chambers - a thrown bone placates them as giant maggots crawl after prey and maggots aggregate to make mockeries of human form with a diseased touch.

The Heart of Corruption

• A mass grave is hidden in the top third of the hill; the source of the diseased flesh which helps make the walls. Bizarrely there appears to always be enough corpses to nearly fill the chamber and even if corpses are removed; the chamber never empties. Giant diseased ghouls swim in this sea of bodies, grazing on body parts and bloating from the feast.
  
• In the heart of the hill is a temple to disease; the corners have festering corpses and piles of ordure. Feverish fanatics are chained to pillars and mutter a litany of praises before iron cauldrons warmed by bonefires. The cauldrons are tended by bloated priests whose curses can rot flesh and their cannibal acolytes who wield poisoned blades.
  
• In the depths of the hill is a cavern that houses a sulphurous spring; the air in this chamber is thick with contagion. A writhing swarm of demonic creatures, all mouth and claws flows around this chamber, guarding the sulphurous spring. Their bites fester with pestilence and they can overwhelm a small group who are incautious in battle.
  

(inspired by this post at Dungeonskull Mountain and the WFRP /40K demon Nurgle)