After I beat the general rush of enemies, why the enemy doesn't generate any more?

I think cartoon wars very hard to win because of it's endless enemy rush. This cause long time battle. So, I make enemy has it's own mana pool. When enemy uses his all mana, he can't make unit anymore. Enemy has more mana every next level.

Also, I think this game too easy. But I think my first game must easy to everybody can enjoy it.

In v1.2,

More enemy units get generated at a higher rate and becomes powerful.