To win I used a strategy of swarming my enemy with around 15 fully upgraded swordwrathes while around 3 fully upgraded archidons fired from behind, shielded by around 2 half upgraded speartons. On the last level I used my first strategy, but while they were killing the statue I saved my money so when the Big Boss came I could swarm it with speartons. Meanwhile, I took out the miners with a spare swordwrath so that there would be no resistance. That is just my strategy, it might not work for you, but that is how I won.
