I know this is an old post, but I think that having to grind separate characters works better. It makes you PLAY the characters and learn how to use them, which will end up better for you in the long run.

I can understand that mentality, but I only have so many hours a day and I like to play a variety of games. I've played many card games and can pick them up almost instantly personally. Having to grind out just to be challenged is not really my idea of fun personally, mostly when I got other games that I want to try or replay that have challenge out of the gate.

Yeah, this annoys me too. There's an achievement for passing Aura 20, which practically forces you to pick one character you like most and stick with them all the way. Playing the same character over and over gets boring. It would be much better if i could play new auras with different characters, but doing all 20 auras with every single one? Nah, i'm too lazy for that and it’s not even needed for the achievement

Maxx your idea is/was spectacular! Heres hoping that something comes from it :)