Well, you could just keep track of the gods you've played against, calculate winrate for each of them and then average.
For example: I've seen Scorpio 15 times and I won 12 games, Lionheart 3 times ad I won 0 times, Jezebel 1 time and I won 1 time, Ferox 10 times and I won 3. The other gods are dead. So the winrate for each god is 12/15, 0/3, 1/1, 3/10 and you expect to meet each god in 1/4 of the all matches, so the probability to win is 1/4*(12/15+0/3+1/1+3/10)= 21/40, so the total winrate is 52,5%.
In this way you can both farm on your account and have more precise data.