The nightborne astronomer Etraeus has devoted long years of research to scouring the skies of Azeroth, seeking answers to the great mysteries of the universe. His scrying has shown him worlds beyond our ken, and the power of the Nightwell allows him to draw upon the essence of those worlds to amplify his own powers.
On Mythic Difficulty, whenever a player shatters, they create an Ice Crystal which periodically causes a Frigid Pulse.
This colossal doom lord, one of the largest and mightiest creatures in the armies of the Legion, was defeated at the Broken Shore through the combined might of the greatest heroes of the Horde and the Alliance. Having recovered from his wounds, Krosus emerges from the bay between the Nighthold and the Tomb of Sargeras to crush any who would oppose the Legion.