I've always said I liked outnumbered battles...but this game has helped me actually be good at them. For a challenge, try only deploying 15 or 20 points of units.
I have a suggestion: How about a few new categories like "Endurance" and "Precision" so that I can find badges for those types of things. Example: The 40-day survival badge for Storm the House 3 should be "Endurance". Get it?