For the duration, you sense the presence of shapechangers within 30 feet of you and can pinpoint their locations in that area. You also learn whether the creature is in its true form or a different form. This spell detects only creatures whose bodies have been transformed in some way, such as a werewolf ’s Change Shape or the Alter Self spell. It doesn’t detect creatures disguised by illusions or other similar magic, such as a hag’s Illusory Appearance or the Disguise Self spell.    The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt.