Kisirani, who no doubt is laughing with maniacal glee right now, says that if you're worried that the zombies might not overtake the world, don't -- things are going to get worse. When a player complains that the buff is easily dispellable, the world event designer jokes that "it sure does seem containable, doesn't it?" It kind of does... for now. But keep in mind that we haven't actually seen Arthas yet (and technically, we don't even know this is him -- it might just be, you know, a mistake in shipping or somethitng like that). Clearly, the Argent Dawn can handle this little "event," and none of us need to worry.
Sure. Just keep thinking that. Meanwhile, more zombies have started appearing all over the world. Mind if I chew on your skull for a bit?
Those of you who weren't playing World of Warcraft back in September of 2005 have probably never seen this footage or heard the extremely entertaining story that goes along with it. That September, Blizzard rolled out the 1.7 patch, which included a brand new raid dungeon called Zul'Gurub. And the final boss of Zul'Gurub was Hakkar, the Blood God and the Soulflayer. (A very challenging fight, until you figure out the trick to it.) And when Hakkar died, he left raiders with a parting present -- a damage over time debuff called Corrupted Blood, which did a reasonable, though not entirely deadly, amount of damage to any players present.
As far as Blizzard's design was concerned, this should have been it.
However, Blizzard overlooked a minor issue -- pets could get Corrupted Blood. And pets could be dismissed while they had the debuff and then re-summoned into crowded areas. (The debuff was short-lived -- so even if a player hearthed while under its effect, they wouldn't make it before it wore off. But when pets were dismissed, the debuff's duration was conveniently paused until they were re-summoned.) And the really fun part is that Corrupted Blood would spread to any nearby players. So, by this method, a few days in mid-September were spoiled for many a player in Azeroth, as Hakkar's plague went through the land, repeatedly infecting and killing players in major cities, while GMs tried to quarantine infected players and Blizzard scrambled for a hotfix.