I'm kind of posting this in case others need help as I think I know the answer.

So, I'm near the end of a game with the Lords and have this guy running round in the south of my map. It will engage units and sack outposts but he doesn't seem to wander far from its starting place. You can't auto-resolve and you can only take one army into the battle.

I initially tried sending an army with a L6 hero unit and all fully levelled (i.e., dungeons are easy), but it took out my hero before I could pile my troops on it, and then its powerful area of effect attack did for the rest of them.

I'm guessing that my only option is to pull one of my two better armies (both with two L10/11 heroes, currently usefully engaged far away)? Only asking because I'm maybe 10 turns from victory and would like to know what you get for beating it.