*snip*
I personally don't see a huge balance issue here in terms of cards.
It seems you don't see an imbalance. Though with this many people (in two separate events nonetheless) commenting on the fact, I would double-check your position. It's almost impossible to balance a game perfectly. In practically every competitive game where there is team customization, imbalances exist. Of course, depending on the severity of these imbalances, yes, skill CAN overcome, but they still exist.
The theme is nice and all, but this at its nature is a competition. That means people want to play to win. They're not here to role-play a battle, they're here to win. The corollary to that, is people don't like losing. If you ONLY chose sides based on good and evil for a competition primairly intended for people to have fun in, then I believe you are coming from a flawed premise. In any event, the theme should be the icing on the cake, and not overpower the cake. In this case, this was originally portrayed as a competitive event for fun. Making (even unintentionally) the teams lopsided impacts the enjoyment had by both sides. If the theme you chose gets in the way of the primary objective of the event (having fun) then you need to choose a new theme. A burnt cake with three inches of frosting on top is not a good cake.
If you are instead using this as an EXPERIMENT as to elemental balance, that should have been stated up front. Then people would not come in with expectations that everything would be fair and even.
I'm not upset, as I'll participate either way, but I'm unsure about what your intended purpose for this is. As of now, it appears flawed. If I am wrong, please show me why. I'm trying to be constructive, so don't take anything personally.