Korchoroth, Siege Runekeeper, is a Super Unique Warscarred Ravager found in Battlefields of Eternity. He is locked in the Timeless Prison along with his Ravagers. Killing him is required to obtain the second Siege Rune for the ram.
In combat, he has Plagued, Arcane Enchanted, Vortex and Nightmarish affixes.