Chaos Ring

Yog-ka dropped this item after his execution. Cygne retrieved it, unknowing of its powers. Cygne held it in secret for a short while before entrusting it's keeping to Ghazgkull. Ghazgkull promised to never give it to another who might abuse it, but the death essence of Yog-ka that he held, along with the ring, combined to prepare his avatar for corruption by the Dread One.

In this state Ghazgkull lured Lissa and Gunny's child, Reh'Dak, to the Sunroof Cavern, and tried to help prepare his form for possession by the Dread One. Finally, after wresting the Chaos Ring from Ghazgkull, he was able to return to a normal state. House Calenture now has both possession of the Chaos Ring, and of Yog-ka's death essence.

Source: Ghazgkull