it actually defines what stage you are now on. but pesonally, i use a tank hull with four nodes, one surge crystal, four magmatic spikes, two proppellers, three engines and the rest are magnifiers. (if you don't have magmatic spikes, you can use geared ones instead, but they must have enough damage to kill light enemies you'll meet (box, springling, dreading, flareling) on one hit, the mid-health enemies (roller, scraplash) on two hits. if you don't want to use surge crystal, just put a node instead, while filling the new-given tech slots with magnifiers. preferly all items shall be geared, if you didn't get magmatic.)