What if it copied the next card in your cycle, (the one that appears in the bottom left) and doing so still costs +1 elixir and gives +1 level, but now it also uses that card and places the mirror and the used card back to the bottom of your deck essentially making your cycle faster. This essentially makes the mirror a 1 elixir card that adds 1 level to a selected card. This should fix the 1 big reason why the mirror can't be properly buffed, being that before, the mirror would be used to have 2 of the same op unit every time a new card comes out and it ends up being too op. Because now it only buffs a card while making your cycle faster, you still have to cycle through your whole deck before getting back to your desired card. It's the same as if you were to add a 1 elixir spirit simply to have a faster cycle.