Blizzard has shared a guide explaining each step of the Scourge Invasion event for the Wrath of the Lich King Classic Pre-Patch. We have also prepared a guide on this very topic, which you can find below —
Scourge Invasion Event Guide
Blizzard
You know the score. The Lich King, perhaps Azeroth’s most infamous villain, is returning. The last time he set his eyes on a goal, it didn’t end well for anyone involved—just ask Illidan Stormrage.