Yeah, I watched the replay and I honestly can't find anything wrong with it. Your communion worked just fine as far as I can tell and magic paths boosted by communion don't show up in the unit inspection screen. Afterall your communion masters did throw antimagic and arrow fend, two spells neither one of them would have been able to cast alone.
So unless you tell what they should have been casting(if it was anything air magic related I assure you it wouldn't have had any effect on the result of the battle) and present some very convincing evidence, I very strongly object turn rewind.
Also, remember that I only had total of six units(opposed to your 200+) in the battle and AI doesn't usually spend gems if the opposing force is considered too small.
So my view to this is that Sauromatia got beaten fair and square this time.
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Renojustin are you going to write a battle report regarding this fight as it certainly deserves one and your reports so far have been enjoyable reading? I'm sure other players agree with this. If you're not interested I might write a report but I'm not as skilled and flavorful writer.