For me, part of the Isolde-Delta Campaign World comes down to closely monitoring complexes, and while the PCs might not have explored their secrets, it seems only natural to decide what type of shape those underground areas are actually in. I ask myself the following questions:
- If the complex has fallen into disrepair or is abandoned, how long does it take before nature starts to reclaim what was developed or built?
- What type of Complex is it – Cavern or Dungeon?
- How was the Cavern formed?
- How was the Cave formed?
- Who built the Mine?
- Who built the Dungeon?
- Does the Complex have a crew that maintains the integrity of it – keeping growth to a minimum/doing repairs etc.?
The secondary reason to use these tables is perhaps your curious whether a specific class of character would be valuable in a certain type of underground complex. One that instantly comes to mind is the Druid, whom has a plethora of spells that use nature to his advantage. You can use these charts to quickly determine if a Druid would be of value in a specific underground setting.