Very stylish looking game! Though I would think of another term to use for the "turn cost", since it confused me. As I understand it, it's actually more of a mana cost (with you simply gaining 1 mana every turn), not a turn cost. Using a spell with 0 turn costs still ends your turn, using a spell with 2 turn cost still just ends 1 turn (your enemy only gets 1 turn before it's your turn again).