I beat two of the three as well!
I've figured out some of it...but there are other things that I'm not sure I understand. I would have expected people with a bow symbol on their attack to be ranged fighters, and thus would be able to attack from the back row, or attack enemies in the back row...however this doesn't always seem to be the case. Several times, I've set the female archer across from someone in the back row, only to find she won't attack them.
Also, I'm not entirely sure what the colors and other buttons are on the left of your collection. I assume the colors are elements, but then there are four buttons to the left of the elements that I don't know what they are. I can't even tell for sure what the picture on them is, actually. The bottom one looks like a grid, maybe?
I might get it too if I get some eStore money for Christmas...as I figure out new strategies, I find it more enjoyable! I wish you could put out multiples of certain cards though. I have 2 or 3 hawks, and a "Moat" magic card (non-arial characters lose 2 attack), which would be an awesome combination!