Shield of Winds

This spell creates a windy barrier that can be felt but not seen. The spell summons up breezes, draws them into thin “threads,” then weaves them into a tapestry of chaotic, whistling gusts. The result is a wall that is nearly impenetrable. No herd of beasts can batter through it; no titan can break it apart. Once created, the shield cannot be moved.

Magical and non-magical creatures cannot penetrate the shield of winds. Nor can non-magical weapons. Gas clouds and whirlwinds are stopped, too, whether magical or natural in origin. Movable objects made of force cannot pass through, nor can prismatic spell effects and the like.

Some assaults do penetrate the shield, however. Purely magical weapons can pass through, provided they have no solid, tangible form. For example, magic missiles can penetrate the wall, but an existing arrow enchanted with the flame arrow spell, or a spear +2, cannot. The following can also penetrate the wall: divination spells, magics such as charm, illusion spells such as phantasmal force, energy attacks, as well as sound and sound-based attacks.

Dispel magic can bring the wall down, while an antimagic shell temporarily negates that part of the wall in its area. The caster himself can destroy it instantly at will. He doesn't have to concentrate upon the wall to maintain it. In fact, the caster can die, leave the area, or undertake other spellcasting without affecting the shield in the slightest.

A shield of winds has no material component other than sufficient air to create the wall. The spell can't function underwater or in other places with a paucity of air.