Easy way to get the challenge: Go into a Two Player match. Then make many sorcerers and recruits. Discard if needed. As player 2, discard a card every turn. As player 1 only attack. Soon you will destroy his castle. Or, you could just build to 100. Repeat this 2 more times. Ta-da! Keep this comment alive at least until the challenge is over!
I just got the best score today, 3rd best score this week, and 4th best score of the month and 4th best of all time. I'm going to rethink my life now...