Sorry Joern, it happens
But yeah, I don't think the Balrog needs to be weakened as the Dwarves will always be wounded on a 3+ (almost) they won't be able to win a fight or even wound the Balrog so it is more of a 'feed-a-dwarf-a-turn' kind of a thing. So it wouldn't matter how many Dwarves you had as you wouldn't be fighting the demon. Let me try *grabs dice and starts rolling* Well, these guys are awesome stone-smashers (as they should be). The mining leader needs to roll a 4+ to wound a D8 structure while the miners themselves roll a 5+, making the mining leader vital. I played a short game on a small map and this is what I concluded:
-How many models can touch the rocks (eg. is it flat or 'sticking out') and how far the miners have to run to get to the rocks changes everything. I had 3-4 miners on the rocks with the mining leader (the rest acting as meat shields) and I averaged about a wound per turn, giving me a total of 5 wounds in 8 turns (they started dying...)
So I think that a W6 D8 rock pile that allows 4 people to hack at it with 6 miners, mining leader, four 'guards' (dwarves with shields) on a board roughly 60 cm/2 feet by 30+cm/1+ foot (width doesn't really matter). So I played a game (Balrog proxyed by a mordor troll base) and:
Good started (by default) and I managed to wound the rock 9 times in 8 turns, surviving with 3 miners and the mining leader. So I would have escaped with 5 miners and the mining leader, less than half.
The winning conditions could be:
Major Evil Victoy/Major Good Victory - Less than half of the Dwarves exit the board.
Tie/Stalemate - The dwarf mining leader is killed (this can be left out as we have and odd number of models)
Evil Defeat/Good Victory - More than half the Dwarves exit the board.
I hope this will help make the scenario better.
As for the dwarves-neutral-evil battle, what if that was part of the final battle where the dwarf king's son is killed as that would be the only time I could see the goblins coming into Moria (they only came later).
Cheers,
Radagast