Kurekas, Imprisoned Demon Lord, is a Unique Subjugator found in the Battlefields of Eternity in Act V of Diablo III. He spawns for The Great Weapon event, as its final boss.
He was absorbed into the malfunctioning angelic siege weapon aeons ago, together with his mount, and corrupted it, causing it to fire at angels and demons alike.
In combat, he has Thunderstorm, Fast and Teleporter affixes, and in addition can conjure a Physical damage Black Hole with large radius.