I found the rules for quicksand but those aren't exactly what I'm seeking. While I am using a marshy environment I want to create terrain which can suddenly give way under the PCs. There are a few criteria I'm seeking from an answer:
- Random surface area. It's not a man-made dungeon here but a vast landscape with variable-sized potentially collapsing floors.
- Random height. I don't have a clear distance to drop (again, not a man-made dungeon) and would rather not model each individual drop after the same pit trap.
- How to determine (for game hazard purposes) when/whether one will open or not? "More weight" is really vague - is there a way to model an increased likelihood? The terrain in question is incredibly volatile so such things would be very likely... What are things the PCs can do to make it more so? Landing after jumping, riding horses, wearing heavy armor, enlarge person are all I could think of.
- Would it be possible (again, game purposes) for characters to use survival to tell if certain ground would give way? Not for the presence of sinkholes - I'm planning on making that horribly obvious. I mean "should I approach that treasure or not?"
- Would characters get a reflex save? Should this depend on what they were doing and/or the width of the opening?
The area I've got portioned off for sinkhole-intensive terrain is a good distance and not easily circumvented without magic. My party will be starting at 2nd level and if they follow my clues will choose to avoid this environment completely, for a while at least. How can I model terrain so that if they decide to challenge nature, she will most likely swallow them whole? Again - not quicksand, but sinkholes. Cave-ins that happen due to cavities below the surface, where the ceiling/floor becomes too thin to support the weight above it.
EDIT: The above model is lacking a few things which I am seeking here.
- How to determine the formula for 1 and 2. Any additional PC-related modifiers that should normally be considered for 3.
- DCs for survival, or any other related skill, and times when a check should be called for. Before walking on? While standing upon? After falling? (kidding on the last one)
- DCs for a reflex save or other relevant check to avoid. Modifiers as well, for the variable width/actions involved.
It just hit me that the encounter level might matter for these. I'm planning on having three difficulties, one set for fourth level characters (the warning), one set for ninth level characters (worse) and one set for fourteenth level characters (nigh-certainty). I plan on barring flight through wind conditions.