EDIT: Scrapped and reworded
I'm looking for two things here: First, anyone have any advice on some good, easy-to-use dungeon building programs (not randomly generated) for use by the pathfinder community.
Secondly, I want the biggest, best, scariest lairs you can think of within the limits of Pathfinder content. Assume people will be living here (with the word people being very loosely defined) and suggest accordingly.
Anything underwater for low-mid level PCs is pretty scary, monsters that are great underwater can be a real problem for PCs who are very much out of their element, and if PCs are relying on magic to keep them alive underwater an enemy or trap with dispel magic can really hurt.
hmm...challenge accepted sir. Well as for programs for building dungeons, are you talking about a mapping program that will help you draw the maps out, or something that is chock full of ideas to populate your dungeon?
If it is for the former, i use a little program called AutoRealm. I use it to build dungeon maps all nice and neat like since people without hands write neater than i do. it can be found here.
http://sourceforge.net/projects/autorealm/
As for a scary lair? Well this lair happens to belong to a powerful conjurer. He has dabbled with tapping into other planes of existence and turned his fortress into an extraplanar nightmare. Every door you go through may be a different plane of existence.
For example the foyer is tapped into the Plane of Fire and acts as such, while the water closet is the Plane of Shadow. (dark things tend to happen in the loo) Anyway the fortress is so imbalanced due to the planar instability, that the PC's conjuration magic may or may not work. (DM's choice) So summoning things and healing things will be much much harder. Or you might try to summon, lets say a fire elemental to fight the ice elemental that you're up against and a dolphin shows up. Or you try to heal someone and instead of healing the with positive energy, they get "healed" with negative energy. The BBEG Conjurer may or may not even still be there but hey, I wouldn't wanna walk in there. Which is why i'm gonna use it against my party now.
I always like the old RoleMaster Middle Earth dungeons. I found them very neat and try to include them into other systems.