At-will, swift action, concentration, DC 21+; you gain the ability to see through solid matter. While you concentrate, you can see through walls, floors, earth, and other opaque materials as if they were translucent glass. The depth you can see through depends on the material:
Material
Max Depth
Wood, earth
10 feet
Stone
5 feet
Metal
1 foot
Lead
Blocked
DC +4: double the depth for all materials (stackable).
You see through the material in grayscale; colors on the other side appear muted.