Darkfallen Advisor

Darkfallen Advisors are liches found in the Crimson Hall of Icecrown Citadel. There is normally one in every group of four mobs you might run into.

Attacks and abilities

 * (25-man)
 * (25-man)

Speculation
Given the name, they could either originally be San'layn who became liches, or simply liches of the Scourge tasked with overseeing and guiding the Darkfallen.