Obstacles and Hazards

Obstacle/Hazard Effect  
Acid tank 1d6 damage per round, or 10d6 per round for total immersion; plus poison fumes.  
  Antimagic field Negates all spells or magical effects.
  Dimensional anchor trap Blocks bodily extradimensional travel.
  Hurricane-force winds Ranged attacks impossible, flight virtually impossible.
  Lava pit 2d6 damage per round, or 20d6 per round for total immersion; plus continuing damage.
  Permanent prismatic sphere Requires seven different spells to bypass.
  Permanent solid fog Move at one-tenth normal speed, -2 penalty on attack and damage (good when coupled with incorporeal monsters).
  Permanent wall of force Blocks most spells and ethereal travel, can't be dispelled.
  Three-dimensional dungeons Levitation/flying required to move between areas.
  Unconnected rooms Teleportation required to move between areas.
Variable gravity As reverse gravity, but direction random each round.