I've used this alot when there was a meeting stone raid from both hordes and allies.
All you do is to go 20yrds away and use blink. BOOM! you're inside.
You can now cast spells on all enemies whos near, and they wont see you! It's really fun to watch the opposite faction go nuts cus they cant see where they are attacked from :P
All they see is a meeting stone. Target allies using the tab button and spam instants for best results, since most targeted instants (except for icelance) has no tail. Personally i find Scorch useful.
I recommend fire spec for long range firespells.
Did a search and didnt find any post on this.