Truesight

Truesight is a special sense, measured in feet, that lets a creature perceive things hidden from ordinary sight.

Within its Truesight range, a creature with this sense:

Can see in normal and Magical Darkness.
Sees any Invisible creature or object.
Automatically detects visual illusions and succeeds on saving throws against them.
Perceives the original form of a Shapeshifter or of a creature that is transformed by magic.
Can see into the Ethereal Plane.

Truesight functions only out to its stated range and grants no benefit beyond that distance.