Slave drones have no BS or CC weapons but do have Electric Pulse allowing them to potentially shock an enemy in CC who fails to attack them. If desperately required they could also perform a CC attack with little chance of success or a Coup-De-Grace to accomplish the Extreme Prejudice Classified Objective.
Electric Pulse hits automatically at a 7 in CC and forces an opponent into Immobilized 2 for 2 turns.
Mimetism makes it harder to hit these drones and they are going to need it since they dodge at -3 for being remotes. Given a roll of 7 in the best of times, this means that it is often more worth while to skip the dodge and use the Drone's fast movement to get out of line of fire. Small silhouette helps to hide them somewhat but since drones cannot go prone, they are really hard to protect.
Drones can be used for a variety of dirty tricks. They can make Discover rolls without the worry of reprisal given their low cost. Similarly they can walk into the area of Mines or perimeter weapons to use them up for more expensive models. If an enemy is approaching near them, they can ARO Engage with a higher chance of success than a dodge and then force the enemy to spend orders to kill them in CC. Electric Pulse will further frustrate their efforts.
Should an engineer or doctor have to enter CC, the drone can also join in by entering base to base and provides a +1 Burst and PH to damage. Not only that but it's Electric Pulse presents the enemy with a difficult choice. Since it automatically scores a 7 with no dice roll required, if the opponent chooses to attack the Owner, they will be Immobilized for two turns after wards. IF, however, they attack the drone, then the owner gets a normal roll against them. This is particularly dangerous of the owner is an Engineer with D-charges...
They can be used to complete the Engineer Classified Objective either by deliberately provoking an ARO to be damaged or risking a jump skill from a height to take an armor roll.
ARO them when you can, and beware that they might try to slow down an active trooper or use up your valuable mines or perimeter weapons. Generally, if you spend an order killing a Drone it is a wasted order, unless you are taking their associated owner out of the game by doing so.
If you are bringing the Obsidiod Med-Tech then it is always worth bringing at least one (and possibly two) drones. They increase his value dramatically by allowing him to be in two places at once. Though you can only use one drone at a time, it can be worth having two so that one can be used to run up field and another placed within 6 inches of a model you will want to doctor or engineer.
Though it may not seem worth bringing one with an engineer, the above examples of dirt tricks are particular valuable in the Shasvastii or Morat Sectorial armies.
Keep in mind that they can't be prone and deploy them to avoid ARO accordingly. The drone is best deployed within one short move of a trooper you will want to doctor or engineer, or right on the edge of the deployment zone if you know you are using it to clear mines. Drones can also be placed in the back field to watch for AD or in more open areas to use a Discover skill on enemy camouflage markers or impersonators.
Active Turn Role
Drones uses are largely to allow their associated doctor or engineer to use their skill to medic/repair wounded troopers or accomplish a few Classified Objectives (as allowed on their cards). Never forget that you can avoid activating them at the same time as the Doctor/Engineer to avoid causing an ARO or activate them to move to a new position at the same time even if you are not planing on using a skill through them.
Drones dodge at 7 due to their low PH skill and being a remote, so staying out of ARO is better. They do have a good WIP and are cheap enough to lose so it can be worth Discovering an enemy camo marker, especially when there is another friendly trooper near by to hold their ARO and attack the marker if it chooses to reveal.
Never forget that they can use the Engage ARO to jump into close combat with an enemy AND that the penalty to for REM units Dodging does not apply to Engage.