Blizzard Entertainment officially announced the development of Wrath of the Lich King, the second expansion for World of Warcraft.
Wrath of the Lich King expansion was released worldwide, introducing the continent of Northrend, the new Death Knight class, and increasing the level cap to 80.
The Death Knight, the first hero class in World of Warcraft, was introduced, starting at a higher level and with unique abilities.
The Ahn'kahet dungeon, part of the Wrath of the Lich King content, was opened to players.
Patch 3.0.2 was released to prepare the game clients for the upcoming Wrath of the Lich King expansion, including changes to the talent system and abilities.
Ner'zhul is transformed into the Lich King and bound to the Frozen Throne in Icecrown, beginning a reign of undeath and conquest across Azeroth.
The Lich King begins to spread his influence, creating the Scourge army of undead to weaken the living forces of Azeroth.
Arthas Menethil, prince of Lordaeron, succumbs to the Lich King's influence, claiming the cursed blade Frostmourne and becoming a death knight.
The Scourge invade the high elves' kingdom, resulting in massive devastation and the eventual transformation of Quel'Thalas into a domain of the undead.
Arthas ascends to the Frozen Throne, merging with Ner'zhul and becoming the new Lich King.
Heroes from Azeroth launch an expedition to Northrend to confront the Lich King's growing threat and the Scourge presence.
Adventurers fight to reclaim the Undercity from the Scourge's lingering influence and other dark forces.
The Alliance and Horde join forces to assault the Lich King's fortress in a bid to end his reign.
Adventurers confront and ultimately defeat the Lich King Arthas in Icecrown Citadel, bringing an end to his reign of terror.
