As the detect undead spell, except as noted here.
You can detect the aura that surrounds undead creatures. The amount of information revealed depends on how long you study a particular area.
Presence or absence of undead auras.
Number of undead auras in the area and the strength of the strongest undead aura present. If you are of good alignment, and the strongest undead auraâ€™s strength is overwhelming (see below), and the creature has HD of at least twice your character level, you are stunned for 1 round and the spell ends.
The strength and location of each undead aura. If an aura is outside your line of sight, then you discern its direction but not its exact location.
The strength of an undead aura is determined by the HD of the undead creature, as given on the following table:
HD Strength 1 or lower Faint 2-4 Moderate 5-10 Strong 11 or higher Overwhelming
An undead aura lingers after its original source is destroyed. If detect undead is cast and directed at such a location, the spell indicates an aura strength of dim (even weaker than a faint aura). How long the aura lingers at this dim level depends on its original power:
Original Strength Duration of Lingering Aura Faint 1d6 rounds Moderate 1d6 minutes Strong 1d6×10 minutes Overwhelming 1d6 days