Sancrist Crystal enchanted to cause armies to attack Elves, the bigger the army the fiercer the hate
Set by the Fae Mhor house Eilservs, & guarded by the Death Knight Asildur, the Kingmaker was half of a plot between the Fae Mhor and the vampires to defeat the Elves & reclaim the surface world.
A prophecy, warning the world of the danger, appears to have originated with the Gods, though it also was delivered by the Goldeneye at Gloiran. It ran as follows:
The Kingmaker Prophecy
The lords of many are the slaves of the Dark
The Guardians of Peace falter resuming their trust
In bootless wars die the champions of the Light
Since time before records was Dark kept at bay
By strong swords and lore, then by dragon's might
Who now remains to defend the gates?
Unholy alliance links fearful enemies two
Forgotten shadowbrethren of the firstborn race
Unliving predators dreaming of conquest
Helpless before the ancient scourge are the masters of armies
Immortal evil and destruction well up from below
Surface world's doom hangs on Wyrmbanes' wyrd
Stolen by the Wyrmslayers, it was disenchanted & broken with Grispere's Hammer by the mage Darson Saemir. Fragments of the broken gem were kept by the Wyrmslayers, and Darson was paid for his services in them.