During the Jedi Civil War a sample of the serum was created by Republic scientists and then replicated a few thousand times to cure the Outcasts during the Republic's restoration of Taris. The Republic had a base in the Upper City as the center of restoration as well as the location where the scientist perfected the cure. However, the Sith armada had taken notice of the planet and invaded. After driving the Republic out, they established the base to be their own. The Sith troopers used the samples of the rakghoul serum for patrolling in the Undercity, for their search of the crashed Republic escaped pods of the destroyed Endar Spire. The Sith had so many encounters with the rakghouls that they ran out of serum by the time Revan entered the Undercity, although some troopers who were killed