ANOTHER thing that needs to be balanced (IMO)
Its the Dangerous Game mastery First of all, how is this a "Dangerous Game"? You get health and mana whenever you kill someone. This is not a dangerous game at all. Now the Double-Edged Sword mastery? THATS a dangerous game. You deal more damage, but take more damage. It's not like you are passing up a fair choice for a risky one either, cause the only other option is to get 1 gold whenever you don't kill a minion. If you are building a mastery page that is supposed to do damage, you are getting this mastery skill. But lets move on...
Have you ever seen someone slowly kill off an entire team or get a kill and escape with just the skimmiest, slimest, littlest bit of health? Have you noticed that whenever an assassin dives your team, even if you get the assassin really low health they still somehow have enough left to burst down 2 or 3 guys before leaving? Isn't that the most annoying fucking thing? Well it turns out that that isn't really the champs fault, its this mastery.
Everytime they score a kill OR an assist 5% of their missing mana and health magically get restored instantly. Now this amount of health doesn't really matter when it comes to huge bursts of damage but it often happens that a single person can dive into a fight, attack and kill one person before the whole team can react, get a proc on dangerous game, and since a major part of their damage is missing now he can fight even more guys. \
Like I could understand it if it gave you an increase in Health and Mana regen after a kill, or had a 30 second cooldown or something, but its kinda annoying right now is all im saying.