Champion Mastery?
Let me get this straight;
You blatantly copied the Worshiper system from Smite, made it worse, count one game with a champion win or lose as a "mastery point", offer no rewards for it, etc.
Yet for some reason there is still no comprehensive player data; how many games have you played with a champion? What role do you play the most? etc.
Was this pointless and arbitrary system REALLY more necessary than completing the client? LIke you scout your competitors, and amidst all the other useful things their clients can do, the thing you really felt was necessary to transcribe was F'ing "Mastery"

I'm gonna have to give this a D+, try harder next time