Mark of the Mundane
CrIm, final effect 14.
This enchanted ring causes the image of very brief mark to appear on someone's knee for just a fraction of a second. The main utility of this item is the instances where it doesn't work. It is designed with no penetration, at a target the magus suspects has magic resistance. If the wearer sees a brief image flicker on the target's knee, the target has no magic resistance. If nothing appears, then for some reason, magic resistance is in play. Admittedly, the target will know a spell was cast against them and fail, but will not immediately know what kind of effect or who did it. The momentary duration and innocuous location will help make sure that most casual observers won't notice anything happening, if the target is indeed a mundane.
Base 1, +3 Sight, +10 for uses per day