Everyone who has been having trouble with green levels listen up. First off you want to have max aura range. The most important thing to remember is that you need to let the enemy get close enough where you can keep your army in aura range. Allow several soldiers to be spawned but try to keep a full row in stock before first skull on time bar. Now when you have enough soldiers accumulated summon them all at once. The key to beating these levels is having a large enough army at one time so it does not matter how many the enemy tries to summon at once. This is the only way of winning those levels that I have personally found to work consistently.
What is the point of putting all of the shield guys with spears together in the 4th city? All they do is spam block and then shield bash. Its totally unblanced.