Among the abilities bestowed upon the Lich King was lordship over death itself. From within his Frozen Throne, Ner'zhul summoned a number of undead to serve him and tested his army against the nerubians of Azjol-Nerub and their mighty spiderlord, Anub'arak. Although the War of the Spider raged for years, many nerubians who fell in battle quickly became bound to the Lich King's iron will. Anub'arak himself was eventually ambushed and slain, rising again to join Ner'zhul's ranks as a fearsome crypt lord.

The Lich King appeared to be faithfully serving his master, but he had in fact hatched a cunning and subversive plan. To that end, he created a small fissure in his prison, pushed Frostmourne through it, and directed his minions to carry the runeblade away from the Frozen Throne. Ner'zhul intended to use the sword as bait for a mighty champion: a loyal subject who would free him and serve as a vessel for his restless spirit. While Frostmourne was positioned to serve its future purpose, the Lich King dutifully proceeded with his demon master's true agenda...

Since arriving on Azeroth, the Lich King had been formulating an insidious plague of undeath, a terrifying disease meant to annihilate humanity and create an army faithful to the Burning Legion. To expedite the spread of this contagion, the Lich King recruited a powerful ally in the ambitious mage Kel'Thuzad, a senior member of Dalaran's ruling council.