I might sound really weak, but I am really proud to have earned the warmonger badge in the Den of Danger with a thief.
I am really early in this kingdom, so have only 15 gold and no powerfull item to prepare (nor gods).
Actually, I did not expect this task to be difficult. But without any magic, gods, nor powerfull items, and with a very limited choice of monsters, that poor thief was pretty naked against any kind of challenges. So I finally won that challenge with a bit of luck, and finally mastering a rather basic technic : mid-fight regeneration.
Up to now, I had spent much time finding an easy solution to compute when you would be able to fully regen fight a monster (recover health quicker than a monster, using all sorts of tricks). But never really investigated those cases where you can't regen quicker than your victim, but still need just a little bit of exploration to complete your health and give that final blow. At least, now, I can properly spot those situations and take advantage of them.