Echolocation

A high-pitched, barely audible, sound is emitted from you. Any surface, including creatures, within a 15ft sphere centered around yourself bounces back the sound. You are aware of the exact location and rough composition of any object in that cone so long as it is not behind full cover. An invisible creature can be seen by you, and cannot be aided by invisibility to defend against your attacks, but still gains the benefits of invisibility against you.