For the duration, you know if there is an Aberration,
Celestial,
Elemental,
Fey,
Fiend, or
Undead within 30 feet of you, as well as where the creature is located. Similarly, you know if there is a place or object within 30 feet of you that has been magically consecrated or desecrated.
The Spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of metal, a thin sheet of lead, or 3 feet of wood or dirt.
You concentrate, and planar beings within 30 feet shimmer with distinct auras. Aberrations twist unnaturally, Celestials emit radiant light, Elementals flicker with elemental energy, Fey glow mysteriously, Fiends darken surroundings, and Undead appear as spectral forms.