Solid Fog

When this spell is cast, the illusionist creates an area of fog similar to the effect of a wall of fog spell. 

However, while these rolling, billowing vapors conform to a wall of fog in most respects, only a very strong wind can move them, and any creature attempting to move through the solid fog will progress at a rate of but 1-ft per 1" of normal movement rate per round. 

A gust of wind spell cannot affect it. A fireball, flame strike, or a wall of fire will burn it away in a single round. 

The material components for the spell are a pinch of dried, powdered peas combined with powdered animal hoof.