After finishing Climbing the Ranks, you'll finally be able to go after the Warchiefs, with your goal being to be kill four of them. Other than the one Ratbag has become a bodyguard of, the other four are completely random. In fact, the weaknesses and strengths of all the Warchiefs are random.
The first thing you should do before anything else is hunt down some Captains or intel, which should be used on the Warchiefs. This will enable you to know any weaknesses and strengths, as well as find out if they have any bodyguards. With this info in hand, find intel on those bodyguards and kill them.
The reason why you want to go after any bodyguards first is because they will join in the fight with the Warchief, making things more difficult on your end. Now, that's not a guarantee that the Warchief won't have other bodyguards in the battle, as they sometimes do have ones you might not be able to get to or kill beforehand.
