WotLK Story Chapter 3: Shattering the Frozen Throne

All of Lordaeron rejoiced at Prince Arthas' triumphant return from Northrend, but their elation was not to last. Not long after Arthas knelt before King Terenas, the former paladin thrust Frostmourne into his father's heart. At the Lich King's command, the fallen prince went on to murder his mentor, Uther the Lightbringer, and claim Kel'Thuzad's remains. When Arthas had finished, Capital City, formerly one of humanity's crown jewels, had been reduced to a silent wasteland of death and despair.

The death knight Arthas then marched his ever-growing army of the undead into the forests of Quel'Thalas, slaughtering the elves in his path as he smashed through the gates of Silvermoon. Arthas laid claim to the legendary Sunwell, using its powers to raise Kel'Thuzad as a lich and leaving the high elven lands utterly devastated in his wake.

Kel'Thuzad in turn opened a gateway to usher in Archimonde, a powerful demon lord of the Burning Legion. Upon his arrival Archimonde declared that the Lich King's usefulness had reached an end. While Archimonde pursued the Legion's goals, Arthas traveled to the continent of Kalimdor. There he met and advised Illidan Stormrage, a powerful demon hunter whose interests aligned with those of the Lich King.

The Third War ended with Archimonde's demise, and Legion forces on Azeroth were scattered in the wake of his death. Arthas returned to Lordaeron, where he was assailed by painful visions that he learned were a sign of the Lich King's weakening power. The death knight journeyed back to Northrend and was confronted by an army of elves: survivors of the Scourge invasion of Quel'Thalas. The elves had joined forces with Illidan Stormrage in order to march on the Frozen Throne. The crypt lord Anub'arak arrived and guided Arthas into a series of ancient tunnels that allowed the pair to reach the Lich King quickly.

Arthas emerged from the subterranean caverns to face one final challenger barring his path: Illidan Stormrage, who had become a demon. Illidan engaged the death knight in single combat, Frostmourne clashing against Illidan's Twin Blades of Azzinoth. Ultimately the demon was left bloodied in the snow as Arthas advanced, undeterred by the voices of the past echoing in his head, warning him against the action he was about to take.

Some say that Arthas was still in control of his own actions when he ascended the steps of the Frozen Throne; others claim that he had been the Lich King's creature ever since taking up Frostmourne. Whatever the case, a single voice stood out in the death knight's mind as he reached the runic armor encased in ice. "Return the blade," commanded the Lich King. "Complete the circle. Release me from this prison!" With a roar, Arthas brought Frostmourne down, shattering the Frozen Throne. He then donned Ner'zhul's helm, sealing his union with he Lich King.
The Lich King waits now, scheming to lure adventurers down the same dark path that Arthas tread. Frostmourne hungers for the souls of both the brave and the foolish, and somewhere Ner'zhul's voice still echoes within the helm of the Lich King.