The drone to the right is our Drone Sentry Turret, which is not a drone by the standard definition, but uses drone technology -as do a couple of the drones on this list. We will get to that later.
Let's get down to the brass tacks.
These are all the drones in the Tau inventory (that I know of), and that's too many for one post. So, I'm going to break them up as follows.
|Part 1||Part 2||Part 3|
|Gun Drone||Grav-inhibitor Drone||Drone Sentry Tower|
|Shield Drone||Pulse Accelerator Drone||Drone Defense Turret|
|Experimental Shield Drone||Recon Drone||Heavy Gun Drone|
|Command Link Drone||Missile Drone||Heavy Gun/Marker Drone|
|Marker Drone||Shielded Missile Drone||Remora Drone Fighter|
|Sniper Drone||Interceptor Drone||Technical Drone|
|Warscaper Drone||Guardian Drone|
They are available in squads of 1 to 3, have no weapons other than BS3 markerlights, but can spot infiltrators and grant one vehicle per turn target lock (split fire). And they are very weak to S4 weapons fire.
What they need is Failsafe Protocols or Flechette Dischargers to inflict a little pain to prevent fast hoardy tarpit units like Hormagaunts from beating the shit out of them before they get a few shots off.
Their weapons options include burst cannons, plasma rifles, missile pods or fusion blasters, and different turrets in the unit can take different weapons choices, but always the same on both sponsons, and always twin-linked.
Turrets have the option of taking a disruption pod or a shield generator, but it cannot take both. (These options are in the FAQ, not IA3).
For 1 additional point per turret you can choose to deep strike them. If you start with the unit on the table, the turrets function as a single unit for the entire game (and 4″ unit coherency). If you choose to deepstrike them they become independent units subject to scatter, etc... with the exception of mishap.
Turrets do not Mishap. They have specific rules specifically stating that they cause glancing hits if they land on a vehicle and are destroyed automatically if they scatter into impassable terrain or off the table. Be very careful how you deploy them.
Technical Drones are the only drones without rules of their own. The only rules I can find for them is one in Cities of Death that adds them to a Firewarrior squad to represent strategems that make them combat engineers (giving them the ability to destroy fortifications)and one in Apocalypse that allows them to repair Drone Sentry Turrets,
Heavy Gun Drones are a natural evolution of the handy Gun Drone. They are larger and heavier than standard drones and carry a pair of twin-linked Burst Cannons. Other than their size, they are barely different than the regular old burger-bot.
A variant of the Heavy Gun Drone is the Heavy Marker Drone, which replaces one of the burst cannons with a heavy markerlight. Real advantage here over the standard marker drone is that this guy has some burst cannon muscle to strafe opposition. Regular marker drones have no offensive capability.
Last on the list is the Remora Drone Fighter is a small flyer stuffed with stealth, seeker, and networked markerlight goodness. At BS10 all around, they are not very durable, but they do pack a couple of twin-linked long-barreled burst cannons for those pesky ground targets. It also has BS3, 2 hull points, hover, shrouded, jink, and is very fast, but at 90 points it's not bad but be sure that you have a very specific need for these little puppies.