This is pretty straight forward. If you happen to be fighting for wintergrasp, and the enemy team wins it, you should be allowed to get some revenge.
So, what you do is start fearing, and mind controlling enemy players into the instance. Chances are, they are already in a raid group, and entering said instance -will- get them saved to another groups Vault, therefore not allowing them to kill the boss for the week.
I have already MC'd a few people in, and one person sent me a msg on an alt, it just about made me cry of laughter, so i figured i'd share it with you all.
Enjoy.
Edit: I didn't think about this until after the Post, but you can actually use this same concept to grief players of the same faction. Simply invite them to group/ give them a summon. If they are summoned into your raid or instance, they will be saved even if you have cleared everything. This Edit'd part may belong in scams and not exploits, but i'm just tacking it on for extra reference, while the actual exploit is up above.