Vatic Gaze( Player's Handbook II, p. 85)
Your arcane studies have brought forth your nascent talent to sense magical auras and the power that others are capable of wielding.
arcane caster level 9,
You can use detect magic at will. Also, as a swift action, you can attempt to determine an opponent's spellcasting ability. You make a Sense Motive check (DC 5 + target's caster level). If this check succeeds, you learn the highest-level spells the target is capable of casting. This benefit grants you no insight into spell-like or supernatural abilities.