When disguised as a human, he went by the name Atarum Prestor.
He hosted a grand ambition to overthrow his father, Neltharion. To this end, he tried to appeal to the other dragonflights for help. For a time, they assisted him, hoping he would be a better Earth-Warder than his predecessor. Vaelastrasz and his brother Ashastrasz accompanied Atrumarion for a time, as the Black Dragon forged alliances and set plots in motion. Atrumarion planned to gain control of the Black Iron Golems of Azeroth which he had helped forge in ages past. Atrumarion, however, was to prove just as insane as his father. The dragonflights abandoned his cause and warned him to cease his mad schemes. Atrumarion ignored them and gained new allies, including Meryl Winterstorm.
Meryl agreed to help Atrumarion, utilizing his identity as Giren to control the Chancellors and gain access to the Black Iron Golems of Gilneas.
What Atrumarion did not know, however, was that Meryl wanted to activate the Golems to set them free from their ancient bondage. When Meryl failed to release the Golems from their bondage, he turned to Men'heva, an old friend and ally, for help. He soon learned that Men'heva wanted to break the timeline to bring about the Age of Men'heva, and with Dartol Caxagord at his side, Meryl fled to Ythan'alai, hoping to gain the patronage of Xaxion Drak'eem. Dartol Caxagord betrayed Meryl, however, and led Men'heva to Ythan'alai.
Meanwhile, Krasus was dispatched to hunt down Meryl for helping Atrumarion. Vaelastrasz was sent directly after Atrumarion.
Vaelastrasz and his brother Ashastrasz found Atrumarion in Gilneas, where the dragon had allied himself with the Church of Kruel. Using the Tome of Eternity and sacrificing Ashastrasz, Atrumarion managed to gain control over the Black Iron Golems of Gilneas.
Then he died again.