This spell creates a thin wall of black smoke. The wall is stationary once created. The wall blocks sight to a limited degree. Creatures on opposite sides of the wall that cannot see over it gain concealment from each other. A creature can pass through a wall of smoke, but it must make a Fortitude save to avoid being nauseated for 1 round.
https://dndtools.net/spells/spell-compendium–86/wall-of-smoke–4745/

