I agreeNaut is one of the more self-sufficient main weapons, it doesn't really need much from its kit to begin with. Sensor has some utility to monitor choke points or tag targets you aren't in position to fight on your own, but you don't want to waste too much ink on it too often. Rain is nice because it's a simple fire-and-forget special, pop it to refill your ink tank and then go in with your amazing main weapon.