Add Skins for Brawlers when Players max that Brawler (F2P Skins)

My idea is to add specific skins for characters that you have maxed. This wouldn't impact the game because if you enjoy a character you will spend elixir upgrading that character and when you've finally reached 15 upgrades you can get a free skin to prove to other players that you have spent the elixir to max your character. This idea is simple to add because there will not be any new features that require complicated lines of code just new skins (that can be found in bunches on reddit). I think this would be a great addition to F2P players because 45 elixir is not easy to come across and after maxing a brawler there should be some additional reward.

P.S. This would not screw over people who bought other skins using gems because these skins would be different and only available through maxing the specific brawler.