First, I have to disappoint you a little bit : the skeletons – archers do not have penalties for shooting at night ), so that the latest intensification of necromancers in the patch has made such a site probably second difficulty after 12 Orc Warrior with Lord). Well, it is the lyrics.
Now about question. Exactly one factor( there is some more but this one – 100%) on which depend all the battle – it is game day of the company – the farther away the enemies will be more, regardless of the difficulty level, your party size or the fame.