Sonic HEDGHUG - Season 3, Episode 13 "Heart of Mobius, Part 4"

The Cluster has awakened, and Dr. Eggman leads a desperate expedition to the very core of the planet to find the center of the entire Cluster hive—and at the same time, to find a way to destroy it. He succeeded, and the ancient machine calling itself the "Overseer" has reactivated after many years. Along with it, the Cluster War continues after all these years.