The Shadowstone

The Shadowstone (known as Kadaena's Heart and the Dark Jewel) was an immensely powerful artifact Kadaena wore around her neck. It was a soul devouring necklace that even the gods feared.The Stone was lost after Kadaena was killed by Ûtha and her body fell through the Gates of the Void, but was later recovered by Gonodbal.It was believed to have retained the soul of its last wearer, which presumably was Kadaena.