There are ways to beat it, by using the cards that have the magic resistance buff; but it seems like the magic/water summoner +1 magic attack can be a bit over powered against any class not using a magic resistant Tank.
Having the spinback turtle tank and 4 cards that hit for +2 magic does 8 health damage to the 1st card each round; furthermore you can protect those cards using the magic attack guy who also gives +2 armor. (forgive me Ima a noob and can't remember what the card name is, its a little rat dude with glasses, uses 5 mana). I personally do very well with this setup, but I know its weaknesses.
I think fire is underpowered against this magic setup since I dont have a magic resistance card to take that massive 1st round attack. I suppose one stratgey is to have the first attack by using the speed buff summoner, but I have yet to be successful. Any suggested line ups (in or around bronze II cards/skill level) are welcome! Thanks for reading!