Difficult terrain, such as heavy undergrowth, broken ground, or steep stairs, hampers movement. Each square of difficult terrain counts as 2 squares of movement. Each diagonal move into a difficult terrain square counts as 3 squares. You can't run or charge across difficult terrain.
If you occupy squares with different kinds of terrain, you can move only as fast as the most difficult terrain you occupy will allow.
Flying and incorporeal creatures are not hampered by difficult terrain.
Chunks of hot volcanic rock and clumps of ash pound down when this spell is cast, dealing 3d6 points of bludgeoning damage and 2d6 points of fire damage to every creature in the area. This damage only occurs once, when the spell is cast. For the remaining duration of the spell, heavy ash rains down in the area. Creatures inside this area take a –4 penalty on Perception skill checks and the entire area is treated as difficult terrain (see FYI box at right.) At the end of the duration, the rock and ash disappear, leaving no aftereffects (other than the damage dealt).
Section 15: Copyright Notice - Pathfinder Roleplaying Game Ultimate Magic
Pathfinder Roleplaying Game Ultimate Magic. © 2011, Paizo Publishing, LLC; Authors: Jason Bulmahn, Tim Hitchcock, Colin McComb, Rob McCreary, Jason Nelson, Stephen Radney-MacFarland, Sean K Reynolds, Owen K.C. Stephens, and Russ Taylor.