Newthough,
I find the idea of a spell that simulates battles incredibly interesting! This is really almost a completely seperate issue from the save game... but what a neat idea!
I'd say the battle would be completely visible (as if it was real).
Probably mid level astral spell. Maybe astral 5, 20 gems. Pick two provences. Spell plays out battle from army in provence 1 attacking army in provence 2.
I'm not sure of the difficulty in implementing it. It possible that it could be fairly attainable... if they can simply que up a battle as normal but not "save"
any of the results.
What a cool spell that would be. Simulating a possible reality.