Optimizing Marker Lights for the new Tau

Let's take a look at some of the options available for using Marker Lights in the new Tau army. Marker Lights are one of the big strengths for Tau. They give Tau the ability to enhance their shooting any given turn to focus on the primary threats.

Pathfinders
This is a good choice. They are inexpensive and can infiltrate. Set them up in a safe position inside cover such that it will force your opponent to make a tough decision to shoot them. They are fragile though so don't put all your eggs in one basket. You need multiple sources of Marker Lights so two units is the way to go since they are low cost in terms of points. Another advantage to Pathfinders is that they are a Fast Attack unit so they aren't competing with your Elite choices.

Commander with Marker Drones
This is another good choice. You can take a Drone Controller to boost their shooting to BS5... Very reliable. Drones are Relentless so they can move and shoot their Marker Lights at full BS which is a major advantage compared to Pathfinders. This is obviously a more costly unit though but I think if you build the right unit it can work well and not be too much of a point sink. You don't need a full compliment of Marker Drones since they hit on 2+ due to the Drone Controller... You're really getting your points back from this unit quickly right away. This unit can also move around and join other units if necessary instead to boost them (e.g., Broadsides or Crisis Team).

Other Choices
You have the option to take some Drones in other units such as Fire Warriors. The major disadvantage here is these units aren't really intended to provide Marker Light support (i.e., primary target priority mitigates their usefulness) plus you can't boost them above BS3. There are other types of Drones that are a better option for these types of units.

Some of the vehicles have access to Marker Lights as well but again this conflicts with their primary targets. There are some options for Target Lock but again you can't boost their shooting to BS5 so really it's some points better spent elsewhere.

Fire Support Tricks - Stacking Marker Lights
Let us take a look at an example where a squad of Fire Warriors will take the charge from an enemy unit. You've placed them in such a manner that they are well supported by other friendly units that can also fire on Overwatch due to Fire Support. For this example the pair of Pathfinder units are both close enough to lend a helping hand. Assume each unit of Pathfinders consists of ten models. The first Pathfinder unit fires... Assume they hit on average with two to three Marker Lights. The second Pathfinder unit can now hit at BS3 to BS4... This means that the third unit to fire on Overwatch (such as the Fire Warriors) has at least five Marker Lights at their disposal. This can make a huge difference!