Sentries, otherwise known as Security Drones, are an enemy type in Duskers. They are robotic drones like your own with a turret mount and limited line of sight. They appear purple in drone view, and are completely ineffectual at their jobs because you can easily outrun them in most cases. They are the only enemy type that destroys sensors, and they aren't attracted to lures. Most importantly, they drop anywhere from 1-3 scrap when they die. But how do you kill them? Well, there's a few ways, listed below in order of preference.

It is worth noting that Sentries, like Probes and other mobile infestations, completely ignore obstacles and even the walls of rooms. They travel through doorways merely because their pathing tells them to. As soon as they peek through a doorway, they stop, shoot any nearby threats, and then travel toward the center of the room. Since they never fully entered the room before heading toward the center, they can end up traveling through the wall of the room in long hallways. If you kill a sentry while it is inside the wall or an obstacle, the scrap could be dropped in an inaccessible position, so it's best to kill them near the center of the room.

Additionally, if a Sentry dies in a doorway, the scrap might be teleported to a nearby room as a failsafe instead of landing in the doorway. If you can't find the scrap, re-examine nearby rooms and it should appear. The Scan module and Shipscan command will reveal it, too, but Probes will not re-scan a room that has already been scanned.

As a last resort if you can't pickup the scrap from a Sentry, you can use the Collector ship upgrade to try and collect it by exposing the rooms to space, or you can commandeer the ship to auto-harvest the scrap.

Before killing a Sentry, you may want to move it into an appropriate room. Sentries have a short line of sight that you can visibly see as a purple vision cone, and they are slow to react. As long as you don't get cornered, you can safely drive up to them and drive away without being attacked. Sentries, like Probes, will patrol all rooms they have access to, so you need only open a route to the room you want them in, wait for them to arrive, and then seal them in the room after you back out.

Some derelicts have ship defenses, wherein some rooms will have a turret bolted to the floor that will kill everything that moves - infestations and your drones alike. They have two requirements to work: the room they are in must be powered, and you must activate them at a terminal using an Interface drone module. After that, they'll kill anything that is already in the room as well as anything that so much as puts its nose across the threshold of any doors leading into the room. If something dies in a doorway, the door will not be able to be closed, so it's best to trap enemies in the room before killing them.

This is a really easy way to convert sentries into scrap: just get them into a room with defenses that you can power at the same time as a terminal with the defense command, and you'll get your free scrap!

The "Trap" drone module allows you to place and remotely detonate explosives that damage everything in a room (including your own drones). A trap does enough damage to kill any enemy type, but can also damage or destroy items in the room like defenses, generators, fuel accesses, and interfaces, and it costs scrap to replace used traps, so it is less desirable than using ship defenses. However, it will guarantee your free scrap from any sentries in the same room as the trap when it goes off.

Since traps are a limited resource during a mission, it's in your best interest to get as many sentries (and other enemies) into the room with the trap at the same time as possible. You can use lures to attract organic threats and sensors to create busywork for sentries, since sentries will stay in a room while they are destroying sensors in that room. Sentries will also be temporarily distracted by lures, but otherwise ignore them.

If you don't care about not being able to close a door, it's alright to detonate the trap with sentries in the doorway shooting a sensor - you'll get your scrap. Otherwise, wait for sentries to finish destroying sensors and close the door behind them. Or, if the room is large enough, place the sensor as far away from the door as possible so sentries have to move fully into the room before they can attack it, since they have limited range.

The "Mine" drone module allows you to place proximity mines. You can't control when they are detonated, and their damage falls off sharply based on distance. Like the Trap modules, mines can damage and destroy items in rooms, and you can only have 4 per module. It also also takes a random amount of mines to kill a Sentry, anywhere from 1 to 2 mines. However, since they detonate based on proximity, you don't actually need to know where the Sentry is, and you will know immediately when it is safe to harvest your scrap.

The "Turret" drone module is one of the few offensive modules in Duskers, and it is terribly imprecise. It isn't very effective against some enemy types, but it works well enough for sentries. Since sentries also have a turret of their own, it's best to abuse their AI - sentries cannot see into neighboring rooms until crossing the threshold, so if you stand in the doorway without crossing into the room with the sentry and activate your turret module, the sentry will be killed as it moves toward the door. If done correctly, it won't die in the doorway and you can even close the door afterward. Sentries also take some time to react to your presense, so you may find it more enjoyable to just drive right up to a Sentry and shoot it in the face.

However, you should first let Sentries move into known clear rooms, because the Turret drone module can actually damage or destroy nearby items in the room. If you attack a Sentry in a room you haven't explored yet, you could destroy the fuel access or a generator.

If you happen to have the Overload ship upgrade and none of the above options are available to you, you can get sentries into rooms with electronics like fuel accesses and interfaces, and then overload them to kill them. The only requirement is that the room with the item be powered. If the item you overload is damaged, rather than destroyed, it has only half damaged the sentry and you will need to use overload a second time to fully kill it. In general, the sentry won't be dead until the item you overload is dead. It may be possible to damage it with one item and then another, however, to avoid permanently destroying the items, but it's completely random whether an item is destroyed or just damaged.

Generators can also be overloaded, but the room has to be powered, meaning you either need to have reroute power or remote power to do that, and it's also a really bad idea to destroy generators that you may need later in the mission.

The namesake of this guide, radiation will slowly kill certain infestation types in Duskers, namely Sentries. However, radiation also damages your drone repeatedly while you are in the radiated room, so this technique becomes a balance between scrap gained and health lost. There are many factors to consider when using this strategy, but if all other options above are not available to you, then this can still earn you some extra scrap (and points, if you play the challenges).

A good room is one that has a door you will be able to access close to the center. The room should also be small or thin so that you can spend as little time taking damage in it as possible. It must also be able to convince sentries to enter the room fully so you can close the door behind them - notably, sentries will not fully enter 1-wide rooms through a door close to the center, and will instead stand in the doorway until they decide to leave.

You also need to pick a room that will be easy to radiate - either via an existing hull integrity breach (pipe rupture or asteroid) or by letting in radiation from an airlock. If you have the Cannon ship upgrade, you can use it on a nearby room (because sometimes it creates a vacuum, which you don't want).

If the room is already radiated, you will want to let sentries in from a room that you don't mind radiating (because radiation spreads and doesn't reset when you close the door). If you have sensors, you can place dozens of sensors in the room to keep sentries busy while you let in multiple sentries or begin radiating the room. be sure to close all the doors as soon as the room is radiated.

You can get sentries into the room all at once (which us very difficult without spamming sensors) or you can let them in one by one, being careful to avoid radiating the rooms you let them in from. Radiation spread does not reset when you close doors.

At this point, you will need to wait for the sentries to slowly die. Their health will tick down slowly and they should die within a minute. If you have shipscan via a terminal, you can repeatedly scan the room to check for the scrap they will drop. Knowing where the scrap is and how much is dropped will influence your decision about if and how to enter the room and collect it.

If you have the Decontaminate ship upgrade, you can cleanse the room of radiation and safely collect the scrap. Otherwise you have to be wary of letting radiation escape the room as you enter it to collect the scrap and then exit it. If you have a Shield drone module, you can use it to safely collect the scrap that way, too, but you still have to worry about letting radiation escape. Otherwise, you'll be taking damage for as long as you are in the room, and the scrap you collect can only make up for so much lost health. If you get in quickly, gather, and get out, it will generally be worth it. Sometimes, however, the scrap may not be in an ideal location - if you have the Collector ship upgrade, you can vent the room and hope some of the scrap gets collected (you will receive a message in the console), but otherwise you should consider it a loss and avoid taking unnecessary damage. Only collect scrap that doesn't take more than a second or two to get to. You may want to create a one-letter alias for gathering to speed up your typing.