Solid Fog

When this spell is cast, the wizard create a billowing mass of misty vapors similar to a Wall of Fog spell. The caster can create less vapor if desired, as long as a rectangular or cubic mass at least 10 feet on a side formed. The fog obscures all sight, normal and infravision, beyond two feet. However, unlike normal fog, only a very strong wind can move these vapors, and any creature attempting to move through the solid fog progresses at a rate of but one foot per movement rate of 1 per round. A gust of wind spell cannot affect it. A Fireball, Flame Strike, or a wall of fire can burn it away in a single round.

[Player's Handbook]

School: Alteration
Level: 4
Rarity: Common

Range: 30 yards
Components: V, S, M
Duration: 2d4 rounds + 1 round/level
Casting Time: 4
Area of Effect: 20' x 10' x 10' volume level of caster
Saving Throw: None

Material Components: a pinch of dried, powdered peas combined with powdered animal hoof (consumed)