"Lord Kazzak (a huge major boss that usually requires a full 40-person level 60 raid to kill) is lured into Stormwind (one of the major Alliance cities, where all new human characters start) by the enemies and destroys Stormwind within 1.5 hours.
After this event the server is resetted and a rollback was performed by Blizzard.
Lord Kazzak must be killed within 3 minutes or else it will turn into an invincible monster. For every kill it will get so many HP that it can't be beaten by anyone. Luring him into Stormwind, basically destoryed Stormwind."
Basically this immortal demon comes stomping into the baby n00b town and just devoured everything in its path, including high level guards, hundres of NPCs, hell it owned one of the endgame DRAGONS.
I'm just imagining the GM on duty getting THAT flood of emails. XD