This, Gator, especially the part about using the bodyguards to deliver the killing blow.That one's not that bad. Death threat, revenge, know their weakness. Copy your save to the cloud so you don't have to do it all over again if you get an epic. Don't bother with exploiting a weakness unless it falls in your lap. It's too much of a pain to set up, because a lot of the time you don't get credit for it unless it's a certain type of weakness.
Apparently letting branded bodyguards make the kill increases your chances of getting the level 25 instead of the epic, so make sure you brand all his bodyguards.