Deyner Ursaring Dreigon, or its real name, Dinnerbone Upside Down, is the God praised by the Devracathians. So far the only one to see him is the Devracath Leader, Endcepticon.
Endcepticon was given this vision when he was little. A story where Notch said a fight sparked between Dinnerbone Upside Down and Grumm, which he then decided to punish them and make them upside down forever eternity.
Dinnerbone's human form seems to be a scientist/doctor which was proven where he uses an account "Dinnerbone" which many thought was an impersonation but is actually real as proven. He plays in a Minecraft gamemode "Ultra Hardcore" with a group of players called "Mindcrack". Where noone realizes, he is actually the real Dinnerbone Upside Down.
Proof of Dinnerbone Upside Down's human form's existence
Dinnerbone Upside Down as described by Endcepticon then drawn.
Grumm as described by Endcepticon then drawn
The magic of renaming an entity " Dinnerbone"