Request: A strongly flavorful Underdark scene while traveling in unexplored areas by those with little Underdark experience (but good spelunking skills), where the local Underdark taints all within with madness and psychopathic tendencies. Horror and psychological elements are welcome.
Challenging for level 14-17 characters, but that's tweakable. Does not need to feature combat, and if it does feature combat it can be anything from the focus to just an additional hazard or even a red herring/distraction to the real challenge. Should provide a challenge where lose of resources (spells used, traveling equipment, etc.) or time (days) can definitely be lost.
Bonus points if there's some connection to a sneaky cabal of black dragons who wish to block drow traffic, but that's optional.
Please stay away from: drow/derro/(really, most humanoids), molds/fungi, anything that would introduce major plot arcs to resolve nicely (like an aboleth), devils, and cosmology-specific extraplanars (like modrons, githyanki, named demon lords, etc.).
Oh, and just to summon our prolific encounter writer - hey @
vincegetorix.