In one of the campaigns I'm running, the players are about to enter a large fight (~50 vs ~50). This includes around 40 regular units, and 6 Player Characters versus around 45 regular units and 5 elites.
I've done 'siege'-type battles before, where each round reinforcements arrive on both sides, but that was only for about a 15v15 fight.
The problem I have here is that, the way the fights work in this specific situation, if you kill the clan leader on either side, the rest of the non-elite units of the opposing tribe will join the victor tribe.
So what are some ways (or battle systems) I can use to get around the player characters ignoring the army in front of them and killing the leader? (Even if protected he can be blasted with ranged — seeing as they are in a very open area, a desert).
Should I randomize what units on both teams enter battle each round? If all the player characters are present, and simply have to fight weak opposing waves of enemies - it might be too easy.
Or is there a separate battle system I can use altogether?