Tau Tactica

Abilities
Abilities are the ‘force multiplier’ that the Tau cadre gets, as they lack special weapons (such as plasma guns).

For context, bolter range is 25, heavy bolter range is 35, and missile launcher range is 45.

Use abilities at the correct time

 * Only use the Personal Shield once the particular squad is under ranged fire.
 * Concentrate all firepower on the markerlight’ed squad. Seek to catch a squad out of position, and ideally running away.
 * Overlapping all of your Tau abilities at once can be simply negated by a well timed Orbital Strike.

Use abilities to counter other abilities
Tau gameplay often involves multiple tactical disengages, to mitigate enemy abilities. Key space marine abilities tend to have a cooldown of 180 seconds. Tau ability cooldowns are much shorter. This means you should re-engage before their abilities come back off cooldown.
 * Photon Grenades counter Word of the Emperor, because though the Space Marines are invulnerable they are not dealing damage in return.
 * Word of the Emperor counters markerlight.
 * The Librarian’s psychic power Smite disrupts a target unit, which can make the markerlight ‘pick off’ less effective.
 * Rhino smokescreen can significantly negate the Tau gunline (reducing ranged damage received by 30%). It is advisable to disengage momentarily.

Use units to counter key abilities

 * Chaos Sorcerer’s psychic power Chains of Torment can be negated by embarking on a Devilfish.
 * Charge krootox into melee just as the Space Marines use Word of the Emperor.

Vespids

 * Vespids hard counter heavy infantry melee units. Sonic Pulse allows you to prevent them gap closing.
 * Vespids counter heavy infantry units (in terms of DPS), but are fragile so can be dealt with by shooting back.
 * Vespid’s provide a source of disruption (via Sonic Pulse). This is useful against Heavy Bolters when you have Kroot. This is useful against Missile Launchers, when you’re vehicle heavy.
 * A common tactic by Tau players is to not reveal that you have Vespids, and then ambush with overwhelming firepower; known in the Tau lore as the Kauyon. Be wary in the early-mid game when you cannot account for the entire expenditure of Tau population.
 * Tactical Space Marines are recommended to seek Heavy Cover to push back Vespids, as Vespids are unlikely to desire to gap close that (because TSM would win in melee).

Stealth Suits

 * Emp grenades stun vehicles, allowing you to destroy them piecemeal. However, Stealth Suits are expensive both in resources and population. Deploying them often means less vespids or delayed vehicles.
 * Massed stealth suits and vespids simultaneously means limited population for Fire Warriors. This means no access to Crisis Suits, which means you’re more vulnerable to Plasmaguns and Terminators.
 * Stealth Suit EMP grenades don’t work against buildings. However, they do disable the production of awakened Monoliths (as it’s a vehicle).
 * The range of the EMP grenade is small (22), which means that your vehicles are only vulnerable if your position has been compromised or the vehicle is out of position.