Objective; Survive 6 waves
You only need to survive 6 waves to complete this level, but the enemies that come at you are hardy, To tackle them, start by using your resources to fully upgrade your rocket tower.
Then build a scout tower on the hill above the base. Upgrade the scout tower when you can.
With your remaining resources, build more rocket towers and upgrade them. The enemies will not get through.
Before the last wave came, I built a slow tower and upgraded it. This will slow the enemies down by half and allow your towers the time to destroy all enemies on the final wave.
Your Guide to: Tower Defense by COM2US 
Ygor
16/06/2013 at 06:31
I would say it is much easier to build a second rocket tower on the top of the cliff next to the base station. Then you build a scout tower next to the slow tower and finaly a third rocket tower on the same place as you. It worked flawlessly even on hard settings.