The developer claims to have added the Black Dragon after Dragon. Most people say that it is real. Others say otherwise. The Black Dragon upgrades from Dragon at 100m exp. People have claimed to have been or had sightings of the Black Dragon. In a recent update, the developer changed the Dragon mass range from 550k - 100m xp to 550k - 5m xp. In the mope.io code, you are not able to find the Black Dragon coded into the game which disproves of its existence. Still, the black dragon remains a mystery.