When a wizard casts Imprisonment, he permanently imprisons a creature deep under the earth.
In-game description Edit
When the Imprisonment spell is cast and the victim is touched, the recipient is entombed in a state of suspended animation in a small sphere far beneath the surface of the earth. The victim remains there unless the reverse of the spell––Freedom––is cast. Otherwise, the victim will remain there as long as the earth exists; rather a horrible fate, actually. If a Freedom spell is cast in the area where the creature was imprisoned, then he will reappear exactly where he was last standing. Otherwise, this spell cannot be dispelled and Dispel Magic will not free creatures trapped in this manner. There is no Saving Throw and the target's Magic Resistance is ignored.