This spell functions like fog cloud, but in addition to obscuring sight, the solid fog is so thick that it impedes movement. Creatures moving through a solid fog move at half their normal speed and take a –2 penalty on all melee attack and melee damage rolls. The vapors prevent effective ranged weapon attacks (except for magic rays and the like). A creature or object that falls into solid fog is slowed so that each 10 feet of vapor that it passes through reduces the falling damage by 1d6. A creature cannot take a 5-foot-step while in solid fog. Solid fog, and effects that work like solid fog, do not stack with each other in terms of slowed movement and attack penalties.
Unlike normal fog, only a severe wind (31+ mph) disperses these vapors, and it does so in 1 round.
Solid fog can be made permanent with a permanency spell. A permanent solid fog dispersed by wind reforms in 10 minutes.
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SECTION 15