Objective: Survive 31 waves
I was able to complete this level using only two towers, focus and laser towers.
I found it important to have a layered defence so that if enemies were able to get past the first couple of focus towers, they would be then picked up by some of the towers nearer to the base.
Towers placed near the base should be used to eliminate all the pink blobs, by doing this you’ll obtain more resources and free up more room to build towers.
Towards the end I built laser towers covering the top and bottom straights. This helps to take out the large groups of fast moving enemies.