More than 300 years ago a volcano was active. To appease its fury, members of a dead cult threw virgin women and treasures into the volcano.
Its activity ceased and there was prosperity for a certain time. The inhabitants of the region built a wall around the crater. A group of priests kept the tradition of the old annual rituals with sacrifices and offerings in gold and precious gems. Rumors started. They said the smoke that went up from the bottom of the crater was the breathing of a demon. Noises could be heard at night coming from the mountain. To ensure unauthorized people stayed away from the wall, noble men demanded the construction of a demonic face in the gateway so it could be seen from a distance.
The priests enhanced their torture rituals with time and started throwing heretics in the crater. Fear started to overcome the people. They built a crane where there was a cage at the tip. People were put there and lowered to the bottom of the crater through the hot smoke that came from the volcano’s hot lava mouth. They then built a spiral with many rooms isolated between them by thick iron gates. The spiral descended to the depths of the crater.
Countless challenges (traps, beasts) were put in the way in each room. The people who were lowered there had to come back to the surface going up the spiral. With each room beaten bigger challenges waited. They never had a chance to escape. Like in every inquisitory process they were considered innocent if they were able to escape the challenges safely. Unfortunately no one could go through more than 2 or 3 rooms without succumbing to the challenges or to the hot fumes coming from the volcano.
What the priests did not count on was that a malign being would arise because of all the atrocity and tried to climb the chains that lowered the cage to the depths of the crater. In despair they destroyed the crane and abandoned the place sealing the main gate. The location was abandoned. And the fumes diminish until ceasing but the evil face in the gateway still continued looking down the mountain.
Many years have passed and now the growls coming from the mountain have returned and with them the smoke coming from it. It is in this context that the inhabitants from the merchant city in the mountain foot come to the heroes asking they deal with it and solve the problem once and for all.. To seduce them, they tell them there are all sorts of treasures there. Gold, jewels, magic items.. All there, waiting for someone to come and get them.
Here is a map of the location: