@ Eldoron

Okay, let's say all the Forsaken want the plague to do is kill stuff.

They've been working on it for pretty much all of WoW. As you discover around level 6 or so as a Forsaken, it can kill living things.

So. They have their own version of the Plague capable of killing living things from the get-go. Once you hobble out of the Forsaken starting area and into Brill, you know the Forsaken have a version of the Plague. Why don't they use it and just wipe out anyone who annoys them? Eventually they make it strong enough to kill Scourge... so why isn't ICC getting carpet-bombed with the stuff? Instead of risking all our lives, why don't we turn the place into a Plague swimming pool and call it a day? A whiff gave Lichy a touch of the vapors... I'm going to guess that he wouldn't do well with a Plague shower. Just because it is 'capable' of turning Vrykul into goo, doesn't mean that's its intended effect (i.e. chocolate is a toxin, it is capable of killing you, but that isn't the intended effect - same thing with alcohol).

I think there is more to it that hasn't been explicitly stated.