mastery requirement for ranked conundrum, how can we lower the champs required for ranked?

right when champ mastery first came out i had the idea to restrict ranked games to champions you have lvl 4 mastery on or above.

i thought my idea was brilliant, i knew it would be awesome to plays with and against players who actually knew how to play thier champ.

i was certain this would be a great idea. but i got one post that i couldn't ignore and i couldn't find away around.

the issue that i feel is preventing mastery in ranking from BEING possible is the fact that you would need 16 champs all with lvl 4 mastery in order to PLAY ranked. just like you need to OWN 16 champs in order to play ranked.. becuase it is theoretically possible, (albeit next to impossible) that if you won less than 16 champs ALL of your champs could be picked or banned..

now if we increase the bans to 5 per team this would make it 20 champs owned and 20 champs to have lvl 4 mastery on.

and for the life of me, i cant find a way around this issue that would be acceptable and allow mastery to be required in ranked.

now i feel 100% certain that mastery requirement in ranked would be perfect if i found a way to solve this issue.

but i really cant find a way around the 16 champ requirement.

so I'm posting this to see if anyone here can come up with an idea that could make this possible. because i cant find a solution to this problem. and as much as i want mastery to be a requirement in ranked. I cant happen unless we find a way around this issue.

So i am asking the community for idea, lets brain storm.. how could this be done?

and even if you don't like the idea of mastery being a requirement for ranked. i feel one of the things holding us back form 5 bans per team would be the increase from owning 16 champs to owning 20.. i feel we could kill 2 birds with 1 stone if we find away to lower the amount of champs required to play ranked somehow