Ranked Gameplay

There should be a system where you have to reach a certain mastery before being able to play a champ in ranked. For example, at least achieving Mastery 5/6 to be able to play them in ranked. This could benefit everyone, including myself, from picking a champ I haven't played or dont know very well. Ultimately reducing the amount of times players pick champs and say "first time" or "new to this champ" and requiring some sort of knowledge before entering a ranked session.