I've been trying to get mastery tokens on Fizz for a few days now. Yesterday I went 34/1/4 in a blind pick game. I received an A-. I had the most gold in the game, and more kills than the entire enemy team combined. My cs was crap, but hey, that's just me, and I STILL had the most gold in the game. I don't know what else I can honestly do in order to get an S. http://imgur.com/a/2nw8a
Getting 79 CS at 44 minutes is pretty bad, practice that. (EDIT: For reference that is less than 15% of th cs that would span in your lane so it means you are last hitting less than 1 in every 5 minions)
As far as kills relating to your grade,they aren't very important. It is far more important to get objectives.
The grade isn't just rewarding arbitrary stats and even if you got 4,000 kills it won't win you the game. Kills only get you gold and time with numbers advantage. They do not progress the game and it is up to your play to "prove" that those kills actually had value. To do that you must grab objectives with the advantage. Otherwise those kills have legitimately no value. You need towers and inhibs to win, not kills. Kills only can help you get tese things but again if you don't get them then those kills are just waste.
cs is an important factor and so are objectives (towers,dragons,baron,inhib). Kills dont mean everything and ur cs jesus lol
