Detect scrying

Detect scrying was a divination spell that alerted one to magical eavesdropping.

Effect
The caster immediately became aware of any attempt at observation by means of clairaudience/clairvoyance or scrying. The spell's effect radiated from and moved with the caster. The spell also revealed the use of crystal balls or other magic scrying devices. The caster knew the location of every magical sensor within the spell's area, if the scrying attempt originated within the area. If the attempt originated outside this range, the caster might receive a visual image of the scrier and a sense of the scrier's direction and distance.

Realmslore
When detect scrying uncovered a spell, a brilliant blue-white flash would burn in the area.

Material components
A small piece of mirror and a miniature brass hearing trumpet.