Abbadomon is a Mega Digimon.
Abbadomon is the final antagonist in Digimon Adventure:, where it evolved from Negamon. It ruthlessly attacked WarGreymon, MetalGarurumon, Seraphimon and Ophanimon and ate the Sora, Izzy, Mimi, Joe and their Mega partners. Then the four who was defeated battles Abbadomon again with the powers of hope emerges from the Digital World and the real world, giving the powers for Omnimon. After Omnimon Alter-S kills the core, Abbadomon then disappears, and says that it and it's core would reborn as a Digi-Egg.