Im at 207 on the "salute" map...Time to quit. I thought I'd try the harder maps, but when you have the earlier towers placed in good areas, it becomes as easy after a little while as the easiest maps.
In my game, the characters that had not been used yet were still decreasing in power whenever the character I was using was getting hit. Also, one of my opponents appeared in my deck after I defeated her. Other than that it was a pretty good operation.
 "Magma Island"){kind=icon}
 "Balloon in a Wasteland"){kind=icon}
 "Methus' Tower Defence"){kind=icon}
 "Learn to Fly"){kind=icon}
 "Cell Warfare"){kind=icon}
 "Bubble Tanks 2"){kind=icon}
 "Duels Defense"){kind=icon}
 "Kongai"){kind=icon}
 "Balloon Invasion"){kind=icon}