You draw wisps of darkness across your enemy’s eyes, obscuring the world around him.
Prerequisite: Ability to cast 2nd-level spells.
Benefit: As long as you have a darkness spell of 2nd level or higher available to cast, you can obscure the vision of a subject within 30 feet as a standard action. If the subject fails a Will save, it treats all other creatures and objects as though they had concealment and takes a –5 penalty on Spot checks for 1 round.
As a secondary benefit, you gain a +1 competence bonus to your caster level when casting darkness spells.
Source: Complete Mage, page 47.