You can detect the aura that surrounds undead creatures. Furthermore, you can detect the aura that emanates from negative energy effects, whether instantaneous or ongoing. The amount of information revealed depends on how long you study a particular area. If you fully study a location, you gain benefits against the threats your power might have revealed.
Presence or absence of undead or negative energy auras.
Number of undead or negative energy auras in the area and the strength of the strongest such aura present. If you are good-aligned, the strongest undead or negative energy aura's strength is overwhelming (see below), and if the creature (or negative energy effect) has Hit Dice (or is of a level) equal to at least twice your character level, you are stunned for 1 round and the power ends.
The strength and location of each undead or negative energy aura. If an aura is outside your line of sight, you discern its direction but not its exact location. Upon spending 3 rounds studying a particular area with stygian discernment, your enhanced knowledge provides you with a +2 insight bonus that you can apply towrad your next attack roll, saving throw, or the save DC of the next power you manifest that affects the undead creature you have located using this spell.
Aura Strength: The strength of an undead or negative energy aura is determined by the Hit Dice (o spell/power level) of the undead creature (or negative energy effect), as shown on the following table:
|HD/Spell or Power Level||Strength|
|11 or higher||Overwhelming|