Celestial Revelation

Celestial light gently descends upon an area you choose within range. Each creature in a 40-foot Cube is affected by this spell for the duration. When you cast this spell, you can designate creatures to be unaffected by it.

For the duration affected creatures are outlined blue, yellow, or violet light (your choice) and shed Bright Light in a 10-foot radius. The outlines can be seen through walls.
As long as you can see the light, an affected creature can't benefit from any Cover (Including Total Cover) as any Attacks and Spells are guided towards the target at seemingly impossible angles or through weak points within obstructions. Attack Rolls against an affected creature have Advantage and attackers may add 1d4 to their attack roll. If the creature is shape-shifted (as a result of the Polymorph spell, for example), it reverts to its true form and can’t shape-shift. Any creatures and objects in the Ethereal Plane there appear ghostly. And any Invisible creatures can’t benefit from the Invisible condition.