D&Dtools1

You cause the target's shadow to become a temporary gateway to a pocket realm within the Plane of Shadow.
The target must make a Will save or be pulled into the gateway; inside the pocket realm he sees a deserted, gloomy duplicate of the real world, while shadowy phantasms stalk and taunt him without causing actual harm.
When the duration ends, the victim returns to the real world and suffers a secondary fear effect.
The victim is frightened for 1d4 rounds and must flee.
On leaving the pocket realm, the subject reappears in the spot it had been in when the shadow well spell was cast.
If this spot is filled with a solid object, the subject appears nearby.
Spells and abilities that move a creature within a plane, such as teleport and dimension door, do not help a creature escape a shadow well spell, although a plane shift spell allows it to exit to whatever plane is designated in that spell as normal (but the target is still frightened upon leaving).