After leaving Tirion to handle the task of raising and reburying the dragons' corpses, Zul'ra did not immediately seek out the Black Dragonflight. Although he had threatened Nalis into a temporary alliance, he was alone after all and could not deal with as many as sixteen Black Dragons.
To deal with the Black Dragonflight and make them cooperate properly with him, Zul'ra decided to imitate the Scourge's Helm of Domination and Deathwing's Demon Soul, forging an artifact that could bind the Black Dragons and make them obediently heed his orders.
With his experience forging the Forest Sword and Fel'dan's Skull, Zul'ra was already well versed in such matters. He took a piece of jade produced in the Zul'Aman region and carved it into a seal, inscribing upon it, "Treasure of Dragon Control." He then wove the power of the dragon Aspects into it. Arcane power was too inferior and could not ensure the item's quality, but dragon power was different.
The dragons' Aspect powers were entirely different from the various forms of magic used by mortals. Each type of dragon power had a different effect. For example, the Black Dragons' power of earth was best suited for forging. Artifacts forged with the power of earth could not be destroyed except through specific methods. The most notable example was the Demon Soul.
The Demon Soul was an artifact personally forged by Deathwing. It gathered a portion of the essence of all five Dragon Aspects within it. It had once annihilated ten thousand demons with a single strike and nearly wiped out the Blue Dragonflight.
With the artifact in his grasp, Deathwing was more than a match for the other four Dragon Aspects, who had lost part of their essence. Yet the artifact's power was ultimately too great, causing the power of