what rider wrote is THE strategy to win, I personally boost one stat towards 60 to have a free armor breaker against any creature to get more easy wins.
On an unrelated note. How does one unlock the gold save slot and if you have finished a game you can't replay any missions?
You can buy any non-legendary/experience/other special card with the red crystals at the marketplace.
Feez to flood the market with cards is bad enough as it is now.