Lucemon

Lucemon is the mastermind behind the chaos in the Digital World. Originally he appeared from parts unknown and ended a civil war between human-five Digimon and beast-Digimon. But his rule was one of tyrantiny, until the five most powerful Human-Digimon and five most powerful Beast-Digimon joined forces to stop him at the cost of their lives. They are refered to as the Ten Anicent Warriors, who will reincarnate as the Ten Legendary Warriors when they are needed.

Lucemon was imprisoned in the DarkArea at the core of the DigitalWorld, and became more bitter. From there, he used Cherubimon and had the two RoyalKnights gather the data he needed to break from his prison. Then he killed off the RoyalKnights once they failed him, and used their Fractal Code to digivolve into the more adult Falldown Mode. Now he was able to combine the powers of light and darkness for nightmarish results. But that changed when Koichi sacrificed himself to unite the Spirits of Light and Darkness into Koji.

This caused Takuya and Koji to combine the power of ALL Spirits into Susannoumon, who seemingly defeated Lucemon. But only the villian's holy-data was scanned, while his Demon-data fused in the DarkArea to become the Draconic Lucemon SatanMode. At first, not even all the kids in Susannoumon could defeat him, until it turned out that Satan Mode's a mindless beast controlled by the Larval-Lucemon, the true form of Lucemon's devil-data. After Breaking their link, Susannoumon destroyed Satan-Mode, which caused the rebirth of the DigitalWorld.

Larval-Lucemon tried to kill Susannoumon, but he 'ejected' the kids out of his body and holds Lucemon as he 'releases' his Warrior components who finished the evil bug once and far all.