What if
- every unit started with a base reputation/fame value
- when you killed a unit in battle, you gained reputation proportionate -- quite a bit if the loser had equal or higher rep than the winner, less otherwise
- when you died in battle, you lost the same amount of reputation that the victor gained
- reputation bonus for winning the Deathmatch
And that would be used for the HoF, instead of pure kill count. If the HoH has been killing powerful heroes who've slain many, its reputation will be high, and he who kills it next will gain correspondingly.