This has gotten so popular on my server that i figured it was a matter of time before someone else posted it.
This is a very simple bug, what you need to do is aggro any mob, wether by shooting an arrow or getting in its aggro area.
I prefer shooting 1 arrow. Anyways, after that use distracting shot and stop hitting him, stop casting, what ever you are doing.
He will keep on coming after you but after a couple of seconds he wills stop and all of a sudden start taking damage, even though no one is hitting him.
The thing is....He is attacking himself! Now you just sit back, relax, and take the loot once he is dead. I have only tested this on Antrix and Ascent servers.
I also suggest that you use an arrow to aggro him as in if you don't get in combat with that mob, he will kill himself but he will be unlootable.
You can use to level, however it takes timing, you have to do the killing blow or else you will end up with no exp, just loot.
I suggest using X-perl considering this shows what your target is targeting, what i mean is, if he is targeting himself and running towards you, then you have done it right and he will start attacking himself, if not then get the aggro off your self and try again.
I hope this helps out considering this is my first contribution. If anyone can test this on Mangos, thank you. Also sorry for all the spaces, I just didn't want this to look all bunched up.