The Faceless Veil, a mystic Working originally devised to throw enemy forces into disarray, and later adapted into a defensive failsafe in case of hostile conquest.
A mental interference effect, obstructing the afflicted's ability to distinguish and recognize individuals, thus rendering chains of command impossible and sewing paranoia and distrust.
The people of Merovin, taught from youth the proper procedures for operating under the effect, hold a distinct advantage. After all, anonymity is an insurgency's best friend.