Skin exchange program and rewards program
A skin exchange program is just what riot needs, it promotes buying mystery skins and trading off the skins if you don't want them and somebody else does, and it also promotes playing new champions. i know that I prefer to play champions i have skins for so the old champions that i don't play anymore, but have many skins for, i can trade off skins with somebody to get a new skin that I like. And a rewards program would be great, not only being a veteran league player should get you rewards, but also having a reward for getting max champion mastery on a champ, or maybe if you gain a ridiculous amount of points you would be rewarded with a chroma. Right now the only real rewards in the game are the free 400 rp you get at the beginning of the game, season rewards for playing ranked, seasonal rewards for contributing in events(such as snow down/ pool party) and the game its self, but just playing the game and getting champions can get old FAST. Lots of people in the world already have all the champions, so all they have to look forward to are buffs, nerfs, and new champions to change how they play or the games they play in. over all i feel like both of these would be very helpful in making league more interesting with out ruining the game.