The Elder Elemental Eye

From Wizards.com:

Adventure Background: The Elder Elemental Eye

Long ago, the Sabrak clan of dwarves, in an effort to restore their clan’s lost power and status, meddled with dark forces in the Sunset Mountains. The dwarves succeeded only in creating their own isolation and madness. Their clan grew smaller and ever more degenerate—so that today, only the three brothers who lead the clan and a handful of other dwarves remain. Of the three brothers, Zarnak, the eldest and most powerful, is a seer whose mind shattered long ago when it came into contact with an ancient evil known as the Elder Elemental Eye... and who now plots to spread the abyssal plague throughout the world.