Kerath was a death knight who ruled as a general on the Isle of Mists during the Age of Darkness. He served under the demon that ruled the island at the time. Kerath was known as The Destroyer and was fiercely loyal to his master. He was entombed in the shrine that held his body before his conversion by an earthquake.
The shrine was discovered later by miners working for the Arcane Order completely by accident. The death knight and the necromentals serving him assaulted the party as they examined the complex. The heroes were able to defeat the creature and his servants.