New Enemy - Automatons / Robots

[Workload]

To bypass some funneling tactics with walls. Maybe add some robots that love power and will come in small numbers. To take power out your batteries, from directly or even any power lines, walls. They will leave early sometimes when they had there fill.
Give them shields if possible that slowly refills when only taking power, can also make then stun or turn off things linked to that power source while taking power. Could also make things short circuit to start fires in your base.
Give them 80 to 100 HP and Shields 100 - Bullets do less damage to shields. Fire could be bad for them if no shields also
Ok range gun
A Solar Flare can be really bad for them shutting them down but they could be advance and still be able to work.