Comet Crash

The Resurgence levels are tough. The enemy has an unlimited arsenal of weapons and money and you are stuck flying around harvesting Thorium and then building one or two towers just to defend yourself. Lasers and Pulsar towers are mandatory. I also suggest building at least two Special Ops towers whose only job is to churn out Thief units. Don't bother attacking directly. The enemy base is in the middle of a spiral so even an attack with a 1000 unit Dragon will not penetrate their defenses (trust me, I tried). The only way to to defeat this level is to cut a path along the left side and then send your Dragon attack in. You could also try attacking with a slew of Switch units and then sending in a squadron of 1000 tanks, but I could never time it properly to work. The following image shows you the path you need to clear;