Source: Complete Mage
The power of elemental air you hold in your mind allows you to exhale the wind.
Prerequisite: Ability to cast 2nd-level spells.
Benefit: As long as you have an air spell of 2nd level or higher available to cast, you can attempt to knock a single creature within 30 feet back with a blast of wind. This requires a standard action and functions much like a bull rush; roll 1d20 + the level of the highest-level air spell you have available to cast opposed by your opponent's Strength check. If you succeed, you push the creature back 5 feet.
As a secondary benefit, you gain a +1 competence bonus to your caster level when casting air spells.