Planescape Campaign
Feat Eyes to the Sky
You have an instinctive sense of when someone is magically watching you.
Prerequisite
Exposure to scrying or greater scrying spell.
Benefit
You automatically spot the magical sensor created by a spell of the scrying subtype (arcane eye, clairaudience/clairvoyance, greater scrying, or scrying) if it’s within 40 feet of you.