Solid Fog

(Player's Handbook v.3.5, p. 281)

Conjuration (Creation)
Level: Sorcerer 4, Wizard 4, Beguiler 4, Wu Jen 4 (Water), Sha'ir 4, Death Master 4,
Components: V, S, M,
Duration: 1 min./level
Spell Resistance: No

This spell functions like fog cloud, but in addition to obscuring sight, the solid fog is so thick that any creature attempting to move through it progresses at a speed of 5 feet, regardless of its normal speed, and it takes 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 falling damage by 1d6.
A creature can't take a 5-foot step while in solid fog.
However, 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.
Material Component: A pinch of dried, powdered peas combined with powdered animal hoof.