Just east of Thrallamar and Honor Hold, there are Infernal Warbringers which have a magic debuff called "Immolation". As a mage, you can spellsteal it, fly into the town of your choice, and kill the entire town (lowbies included) from the comfort of your own flying mount, as the debuff hits for 9k and crits for 18k.
Yes, this is pretty much a repost of "Huge AoE buff for 2 minutes as mage". However, in that post, he used it in Isle of Quel'Danas, which is pretty much useless. I'm pointing out a much better use of it, which is the destruction of towns.