|Although this article is based on canonical information, the actual name of this subject is conjectural.|
After materializing in Wolfram & Hart as a ghost proceeding the Battle at the Hellmouth, Spike became to randomly vanish and reappear at random, with each disappearance becoming longer every time and harder for Spike to return. After confiding in Fred that he was slipping into Hell with every disappearance, Fred worked tirelessly to find a way to re-corporealize Spike to prevent him from going to Hell for good, eventually succeeding in creating a machine to do so.
Unfortunately, Matthias Pavayne, a ghost who was revealed to be the one responsible for Spike's slipping into Hell, threatened Fred's life to force Spike to choose whether to save himself or her; Spike unhesitatingly chose to save Fred and threw Pavayne into the machine, re-corporealizing Pavayne and thus allowing Angel to defeat and imprison him.
Function and design
The machine was a large, room-sized device designed to restore ghosts to corporeal form, though it only had enough power for a single use. Fred described several of the machine's components as "practically non-existent."