Spore Assault by Benicus the PooAvenger
The Lichen Grotto encounter could be placed anywhere a DM could find imaginable. It might be as simple as a cave deep within the underdark to break from the monotony of random encounters, it might be a cave hidden in the wooded hills above a desolate farming community to give a sense of the cosmopolitan faces of evil and monsters in the world, or it might even be in the Shadowfell as a long undisturbed area not fit for human eyes. Whatever the location, the Lichen Grotto is sure to give a long session worth of fun and adventure.