Khaine's Ring of Fury

Khaine once had eight rings, or so the legends tell. Hekarti, Goddess of Magic, designed each of them to embody a single Wind of Magic. Vaul, the Godsmith, wrought them with all his cunning, binding to each a glittering gemstone that shone with the power of the winds. Khaine was much pleased with these gifts, for they gave him a mastery of magic which he had never before known. Yet the Lord of Murder was not to keep his prizes for long. Neither Hekarti nor Vaul had any love for Khaine, and had fashioned the rings out of fear of reprisal, rather than for filial duty; moreover they worried for how the godly balance of power would be altered by what they had done.

Thus did Hekarti and Vaul, whose love for each other could have filled only the very meanest of vessels, then conspire together to see Khaine divested. So did they tell Atharti, the Lady of Desire and most covetous of all the divine host, of Khaine's new treasures, hoping she would distract the Lord of Murder long enough for the rings to be reclaimed. Atharti immediately resolved to take the rings for her own, but Khaine would not part with them, no matter what seductive wiles she brought to bear. Eventually, they came to blows and, in the process, the rings were lost. To the great dismay of all who sought them, the rings had fallen into the mortal world, where Asuryan's law forbade the gods from treading. Over the centuries that followed, only one ring has been found, the black iron Ring of Fury. It has been brought to the battlefield only at times of greatest need, for no one wields the power of the gods lightly. Fewer still find it wise to so openly taunt the Lord of Murder with his loss...

Source

 * Warhammer Armies: High Elves (8th edition) -- p. 64