How to fix the instalock new champion ranked!!!

With the new champion mastery coming out really soon this could be a great way to gate players who haven't played a champion from instantly trying to obliterate the world with a champion they haven't played. Using this system summoners can level up fairly quickly with 10 games or so which is good enough time to make sure that they know how their champions mechanics at least work. http://i.imgur.com/A3jsNKR.png Make it so they must be Tier 3 to at least play a certain champion HOWEVER the only thing I see flailing out of control with this is people who have already played with champions they know in ranked having to go through games that they don't need. so, just take champions the user has already used in ranked and put it in a separate white list and add any newly bought champions in a sort of blacklist this list would be available for the summoner to see. This way everything can stay the same to what it is now but without the person who just bought and wants to try her out jungle!