Hello there, I have been lurking around for a while and decided to finally post something. I have done numerous searches on this and haven't found anything. I will try to explain this with Screenshots as well as I can. I also apologize for large pictures.
This 'Exploit' if you will, involves you flying up onto a tree located right next to the Horde Graveyard in Wintergrasp. You can attack through the tree even though there should be a clear LoS problem, this is mainly for Casters although warriors can do it for teh lulz. The only downside to this is if they catch on, they'll most likely stay at the graveyard with Spiritual Immunity.
The location is here:
Where you need to Stand is here:
You can also see in the picture above that my Serpent Sting is hitting the NPC from the tree. Usually NPCs would just Evade most damage but players can't. Meaning you can roflpwn them and they wont even land a move in.