During the events of Final Fantasy VII: Advent Children, Sephiroth again plays the role of the destroyer. It has been two years following the defeat of Sephiroth, and a fatal plague called Geostigma has spread throughout the world, afflicting many with extreme fatigue and open sores on the skin. This plague is revealed to be caused by Jenova's remaining consciousness in the Lifestream, and primarily affects children due to their weaker immune systems. This disease has also affected Cloud, who experiences visions of Sephiroth numerous times during the film.
The now-reclusive Cloud finds himself confronted by a strange trio of silver-haired men who are the physical manifestations of Sephiroth's will and spiritual energy, his powerful will having allowed him to pull out of the Lifestream before being fully diluted. However, without a great abundance of Jenova's cells, Sephiroth cannot be fully reborn. These three, Kadaj, Loz, and Yazoo all believe themselves to guided by their "mother" Jenova, but rather it is Sephiroth himself who forces their actions. The leader, Kadaj becomes the vessel of Sephiroth after absorbing the contents of a case containing remains of Jenova, transforming into the man himself. Sephiroth reveals his new plan is to use Jenova's influence over those infected with Geostigma to control the planet - once they die, their tainted spirits will join the Lifestream and further infect it with Jenova, until Sephiroth can control it. Then, he will use the planet to travel the universe, and find another planet to rule over.