Case the Joint

You touch a willing creature and grant it the ability to see into and through solid matter out to 30 feet for the duration. To the target, solid objects within that radius appear transparent and don't prevent light from passing through them. This vision can penetrate 1 foot of stone, 1 inch of common metal, or up to 3 feet of wood or dirt. Thicker substances block the vision, as does a thin sheet of lead.

If you cast the spell two or more times before taking a long rest, you must succeed on a DC 15 Constitution saving throw or gain one level of exhaustion.