Driven by rain or another desire to seek shelter, the PC’s stumble across a cave that wasn’t on their map. Off to the side of a well known, but not high traffic trail, the cave is not hidden at all, but out in the open and clearly visible.
Once inside (perhaps coaxed by the subtle near lightning strike), players may note some oddities. First, although the cave doesn’t bear any carving marks to show the work of humanoids, it is rather regular in design. Second, the cave seems new formed, without any dust or debris on the floor. Third, it bears no signs of habitaion.
If and when they decide to strike out deeper into the cave system, they can see it follows no set plan, but does have areas that could easily become rooms if a stout door was fixed to a wall and currently has crude but very well hidden secret doors and passages. Perhaps in some of these passages, gems can be found.
Randomly, without any design outside of chance, jellies may be encountered. No molds or fungus that is associated with older dungeons can be found, but jellies, possibally acting as a type of parasite similar to a lamprey, could be encounted and present hazards to the players. One new type of jelly could present the players with some unique challenges. This jelly, called a stone jelly, is specalized to follow the dungeon worm around.
The stone jelly moves through rock. Solid rock, no matter how thick, is it’s enviroment. It has psuedopods that it uses for manipulations in the world outside stone. It uses these psuedopods to acquire and digest gemstones and minerals. Unless they players can devise some kind of plan to expose the stone jelly to air, mud or some other non-stone enviroment, the players only tactic to drive off the stone jelly will be to attack the psuedopods. The stone jelly can be harmed by normal weapons and attacks mainly by crushing with its arms. If exposed to a non-stone enviroment, the stone jelly loses 20+2d10 hp a round.
After some quiet looting and some dangerous moments, the players come across the lair of the dungeon, a massive cave hollowed out from the surronding rock and containing only one thing. A giant cocoon type pod, twenty to thirty feet high, appanently made from spun stone. Faintly translucent, the vaguest of outline can be seen inside.
Several things can now happen.
The cocoon opens and the players face a newly formed monster.
Things can be seen moving inside the cocoon and begin to work on breaking it open, giving the players enough time to decide to fight or flee.
The cocoon is newly formed and can only be seen as a great worm-like creature. Players may be able to stick around and actually watch the metamorphisis of worm to creature.
I firmly believe that Ria Hawk would have and probally will post an adventure similar to this. Her “Lifecycle of the Dungeon” discussion is thought and plot provoking and very imaginative. Good work!