So I was turning in some quests in Icecrown on this small ledge very high up on a cliff. When my 5 shaman came in to land an Alliance warlock quickly mounted up and flew away. I thought nothing more of it.

So as I am busy talking to the NPC the warlock comes back and attacks my group solo.

Pro tip: Do not attack people that can knock you back when you are standing on the edge of a very high cliff.