blindsight

A creature that has blindsight can see normally regardless of how obscured an area is and regardless of whether creatures or objects are invisible. Blindsight usually has a radius, beyond which the creature relies on its other senses.

Published in Monster Manual 2, page(s) 216, Monster Manual, page(s) 280, Divine Power, page(s) 159, Monster Vault: Threats to the Nentir Vale, page(s) 122, Rules Compendium, page(s) 168.