Tesla Turret

Turrets only exist during Martian Madness, and they do not arrive on their own. A Martian Engineer builds one and walks off, leaving it bolted in place until you knock it down. It cannot move, it never stops firing, and destroying one adds nothing at all to the invasion counter, so every second spent on turrets is a second of the event you are not getting paid for. The fix is to make engineers your first target every time one appears. Let them work uninterrupted and you end up fighting through a fence of the things.

There is a short window while a new one is being assembled where it cannot be hurt at all. It will still injure you if you walk into it during that window, so do not try to rush one down as it appears.

The bolt is not aimed at you exactly, it is aimed somewhere in your direction, and the cone widens the nearer you stand. Standing right on top of one, the scatter is wide enough that shots can leave in completely the wrong direction. It is at its sharpest when you are lined up flat alongside it or directly above or below, and at its worst when you sit diagonally off it. That is backwards from most enemies and it means backing away to a safe distance is what makes you easy to hit.

Hitting it also shoves its next shot back, so keeping any pressure on one keeps it quiet while you deal with whatever else is in the room.

Most of its bolts leave you Electrified, and that debuff punishes you for moving. During an invasion you are moving constantly, so it lands as real damage rather than an inconvenience. In a stretch of ground with several turrets on it, the reapplications overlap and you can lose a fight to the debuff rather than to anything shooting you.