Just a small idea I had - probably could be fleshed out more, but whatever.
Immortal Otyugh/Fallen Druid/Ultharid + Pulverizer usually is cause to scoop, because under that setup you'll be hard pressed to win (you can't draw extra cards and you can't play creature abilities). Also, Rainbow decks are the dominant decks in t50.
Soo...
What if cards became more expensive as they were used more and rare when their usage statistic surpassed a certain ceiling? That would stop people who are playing t50 for farming or money reasons from instantly losing when the setup above happens, which can happen as soon as the first turn. It would also increase the diversity of decks played in t50.
So as to be more 'noob friendly', after the final 500 score quest, a new player would have access to a bazaar where rare cards could be bought only once. That way they aren't left in the dust by people who have already been playing for a large amount of time, and they don't have to spend most of their lives farming for rares.
Also...I'm against Miracle becoming common. If it isn't disregard this message, but I think cards that can change games like Miracle can shouldn't be able to be bought.