[2019] When you hit mastery 7 on a champ you should get to pick one free unique eternal

Had the idea reading over the dev update thread. Paying for achievements is kind of dumb and while making commons available for blue essence twice a year is good, I understand riot is a business and needs to monetize (announcers pls).

I feel like this is a good opportunity to update the mastery system with a real reward for hitting mastery 7. Let people pick a unique or even make it random when they hit that milestone. Maybe give them a common at mastery 5.

Granted given Riots... dubious... history with coding themselves into a box from what I've read this might be impossible but just a thought of a solid way to give some people an eternal they care about while having a more robust experience behind a paywall.