On League of Legends rewards:
I think it's a really cool perk to boost adoption. One thing I've seen though is that you get no reward per assist.
In this game 1/5 characters are always a support which means they kill no minions and let teammates get all the kills so that the damage dealers do more damage.
So if you choose to go support you will get scores like 0 kills 6 deaths 30 assists with 5 minion kills in 50 minute games. While that's a pretty good score, this current reward system doesn't recognize it.
A small reward for assists would curb that.
I started playing LoL only couple weeks ago (when DGB bonuses were added), and I have to say that I definitely agree with this. There needs to be a bonus for champion assists.
People seem to only care about champion kills and won't help damage them, they only step in at the end to try and get the killing blow.
Also as mentioned above, support classes are at a disadvantage for DGB bonuses.