Last level strategy = build nothing but collectors around the bottom area and up to the drone item, then build 2 drones as fast as u can and get them to hit either side of the middle creeper where its pooling, this will give you enought time to get artilery there and get up and running
Would be nice if they told u what the shapes did, i got to lvl 16 and thought , oh whats that green star?? ill see what it does. .... GAME OVER ... wtf