Blindsight

Blindsight is an ability in which you gain the ability to sense your surroundings as if you could see everything, regardless of lighting, concealment, cover, or the condition of your eyes, sensory organs, or mechanical sensors.

Blindsight is expressed as "Blindsight X", where X is a number.

While active, Blindsight X allows you to see everything within X squares, ignoring concealment, cover, or stealth.

Enemies cannot gain Combat Advantage against you if they are within the radius. You may still be Flat-Footed, however.