This is my contribution to my local game group's tactica collection: The Tenets of 5th Edition. The first chapter was LoS, and I decided to add my two cents from a T'au perspective. Feel free to comment or read all the entries at Theassaultphase.com!
Line of Sight and Tau
5th ed. For Tau really brought us lots of new goodies to really amp up our army with. For starters, you can’t consolidate into other units after sweeping advance. Secondly, and most importantly- if you see a guy, you can shoot him! That’s a huge boon for Tau. This brief tactica will elaborate more on the points of how to use true LoS to your advantage.
Firstly- spotting. Every Tau army should have some form of force multiplier, which usually comes in the form of Markerlights. Pathfinders no longer have to worry about a Space Marine squad running behind forests to the lines and not being able to light them up for annihilation. Markerlights hit- no wounds- so no cover saves can be taken against a markerlight. If you can see a Space Marines foot, you can light him up, and deny him a cover save. Firewarriors can now blow the snot out of something regardless how far the squad may be inside area terrain. Perhaps an opponent deploys conservatively, and completely hides a unit? That is where Tau mobility comes in. LoS can be achieved by a wide variety of means. Accurate deepstriking, Crisis Suits, Stealth Suits, Devilfish, Hammerheads, Broadsides with Advanced Stabilization System just to name a few. In almost any case- a smart player will be able find a way to see an opponent’s models.
Any Tau player knows for a fact that his army is not invincible. Quite contrary, Tau take hits probably the worst of any army. Making cover saves against insta-gibbing weapons (damn lascannons!) can still be quite harrowing, and the preferred alternative is to completely hide a unit. On terrain-heavy maps, put your units that you are hiding behind a building or statue. If the enemy cannot see you- they cannot shoot you. Failing that, you can hide a unit in the open by using your vehicles. Devilfish and Hammerheads take up quite a bit of space, and they have armor values (Next best thing against anti-infantry fire!) My preferred tactic to provide protection to my troops is to use my two Devilfish and a Hammerhead to form a protective wall and jump my Crisis Suits from behind, to in front, to behind again. This strategy also works well when you are bearing down aggressively on an opponent’s objective- especially if you have scoured all the anti-tank from the area. They would just see a wall of tanks they are unable to kill rushing towards them with no ways to even hurt it. While completely hiding models may be the best way to prevent death, there are a number of situations where it is okay to place units in the open. Fast moving Piranha, Hammerheads with D-pods, and Stealth suits all have ways to ensure their protection while remaining completely visible. Use these safe-measures well!