I played Heros of the Storm and I really like their system of being able to try out a champion before you buy it. It does not give you points or anything but it allows you to see if you like that champion before you buy them. This would prevent people from using returns on champions. It also allows lower level players to try out 6300 champions and then save up for it. Just a thought.
-Frozenfreez
The thing is they have a bunch of training elements in there to begin with, such as being able to spawn minions and reset the map and the like. It isn't a bad idea if Riot is willing to set aside a game mode just for training (i.e. not how to learn the game like the tutorial and intro bots), but at the same time the whole idea of letting people try out a champion before purchasing is sort of already executed in the free rotation system (which incidentally, I like that Riot isn't like Blizzard in that regard and doesn't make free rotation slots a level-up reward).
Also consider that realistically speaking the characters on HotS are a bit overpriced in general compared to on League (I mean in the sense of how quickly you can earn the gold...without daily quests, you get practically nothing per game. With champs being worth like 10,000 and 7,000 gold and each game without boosts having a base amount of 10ish gold? yeah....). I'd imagine that the time it takes to get a 6300 IP champion on League is less than what it'd take to get the most expensive champions on HotS.
In regard to people using returns on champions, I don't think that'll ever be prevented. There's a bunch of resources regarding each champion so you know exactly what you're purchasing before you get it (champion spotlight videos from Riot.....videos from YouTubers on PBE.....actual videos in the client showing the kit....tips on how to use the champion and how to play against it......etc.), yet refunds still happen.
