I made a list of around 20 battles jotting down my stars, opponent stars, and battle points won (and won/lost), and damage dealt/received. Could not get a working formula out of that... (and the formula is NOT in the rules. Just read what is asked for ) So maybe if one looks at the above and what card defeated what cards. (wild theory: for each winning card of yours get (opponent stars-your stars) ctz. (Min 1), add up for all winning cards, add something for winning battle) Might also be I wrote something down with a mistake, don't believe that, though.