Another way to help the instant resolve work well: Emulate the battle first, and then have the hero or general say what he expects the results to be (and be mostly correct) something like:
We've got some good intel on this group, we expect to be able to crush them with no casulties.
They look quite strong, but we should only have light losses if you provide magical support.
This is a close one, my lord. Possibly you should lead it?
These are hopeless odds. Leave us to our fate.
Ie generally the auto resolve should be an option for trivial battles that are not interesting - ones where the conclusion is prety certain.