You literally see the emanations of magic around you.
Prerequisite: Ability to cast 3rd-level spells.
Benefit: As long as you have a divination spell of 3rd level or higher available to cast, you can sense magical auras (as if you had cast detect magic). The range of your detection is equal to 5 feet per level of the highest-level divination spell you have available to cast. Activating or concentrating on this ability requires a standard action.
As a secondary benefit, you gain a +1 competence bonus to your caster level when casting divination spells.
Source: Complete Mage, page 44.