Dark Masters

The Dark Masters were four Mega-level Digimon who came to rule the Digital World while the Digidestined fought Myotismon in the real world. When the Digidestined returned to the Digital World, they found that it was a mess and that the Dark Masters had taken over everything. The Dark Masters re-configured the Digital World into Spiral Mountain and ruled from the fortress at its peak. The four Masters were Piedmon, Puppetmon, Machinedramon, and MetalSeadramon. All were eventually defeated by the Digidestined and their Digimon friends.