Mark of Detection is a dragonmarked feat, associated with half-elves and House Medani in the Eberron campaign setting.
With this dragonmark, adventurers may roll twice on a Perception check and use the higher result. They may sense the presence of magic as if trained in Arcana, and may use Perception instead of Arcana for the check. They may master and perform Banish Illusions, Eavesdropper's Foil, Scry Trap, and all divination rituals as if they had the Ritual Caster feat.[EPG:90]