Hypotheses.At best  you are only going to get hypotheses.

The only people( the programmers ) that really know the answer are not going to post here..

There are those that study this kind of thing, some may be willing to divulge their research, and the fly in the ointment is, once it gets out, bang goes the advantage, especially as the programmers don't tell anyone when and if they have changed anything.

I don't think that someone will share his battle mechanics knowledge here. Reason behind that is simple: nobody (except developers) is 100% sure how it works - as WDYWTNTF said. Quite a few players figured out how battles results are calculated, they spent hours on testing different hero/shaman/gems/runes/aesir setups and came to few conclusions. And now we are coming to my second, more important point: they won't share it with strangers, because such excessive testing requires time, money and knowledge, which are not coming free of charge. They are sharing it with closest game friends, sometimes on closed Line/Discord groups. Last people sharing it in public were WWM and Nicky Poo on youtube, that's a good starting point. But don't expect that someone who spent hundred hours on testing (and plenty cash) will present you results on golden plate.