An interesting combo for Tau that I don’t think has gotten much attention is as follows:
-Darkstrider (Tau Special Character that costs 20 MB, has BS5 and, among other things, reduces the Toughness of his target by -1T for any shooting attacks made by himself or his unit)
-Tidewall Gunfort Fortification (55 MB cost), which is made up of 3 x Tidewall Gunrigs (Gunrigs each have a TLed Railgun with solid shot/submunition ammo, can move 6″ a turn, provide a 4++ cover save to models behind them, can only be controlled by Tau units, and allow friendly Tau units on them to re-roll 1s to Hit for shooting attacks).
While the Tidewall Gunfort cost is not cheap (i.e. about the same as a Land Raider), they provide significant cover and shooting boosts for Tau units located on them, plus they can move 6″ a turn like vehicles (so good for getting objectives), but models on them count as stationary for purposes of shooting.
Most importantly, the Tidewall Gunfort has a rule called “Coordinated Strike,” which allows a single model to shoot all three TLed Railguns using his BS, as long as they shoot at the same target, and granting a bonus of Armourbane to the Solid Shot ammo and +1S to Submunition ammo.
Combine this with Darkstrider and his BS5/ability to lower enemy target Toughness by -1, plus the ability to benefit from Markerlights still for Ignore Cover, and you have VERY accurate shooting that can be devastating to vehicles, monstrous creatures, heavy infantry, and light alike (and don’t forget, the TLed Railguns have a 72″ range, so they can easily hit anything on the board from turn 1 on, especially when combined with the Tidewall Gunfort’s mobility to help it draw LOS to key enemy targets).
Doing the Math Hammer, here is how the Gun Fort performs against a variety of targets —
*Against AV14 Vehicles:
–>3 x TLed BS5 S10 AP1 Armourbane shots*(97% chance to hit)*(84% chance for penetrating hit)*(33% chance for Explodes result) = 80% chance of destroying an AV14 vehicle in a single Shooting Phase
*Against T6 2+/5++ Dreadknight:
–>3 x TLed BS5 S10 AP1 shots (with -1T on target due to Darkstrider) *(97% chance to hit)*(83% chance to wound)*(66% chance for failed Invul save) = 159% chance of “Instant Deathing” Dreadknight in a single Shooting Phase.
*Against T4 Orks hordes:
–>3 x TLed BS5 S7 AP4 Large Blasts with Ignore Cover (due to Marker Light hits)*(average of 5 Orks hit per Large Blast)*(83% chance to Wound) = 12-13 dead Orks on average in a single Shooting Phase (no FNP and ID on any Ork with multiple wounds, since it is reduced from T4 to T3, thanks to Darkstrider).
*Against T5 Devastator Centurions behind an Aegis Line:
–>3 x TLed BS5 S10 AP1 shots with Ignore Cover (due to Marker Light hits) *(97% chance to hit)*(83% chance to wound) = 2-3 dead Centurions in a single Shooting Phase.
*Against T4 Wulfen with FNP:
–>3 x TLed BS5 S7 AP4 Large Blasts with Ignore Cover (due to Marker Light hits)*(average of 3 Wulfen hit per Large Blast)*(83% chance to Wound) = 7-8 dead Wulfen on average in a single Shooting Phase (no FNP and ID on all Wulfen, since they are reduced from T4 to T3, thanks to Darkstrider).
Bottom line, while not cheap, the Tidewall Gunfort/Darkstrider combo can form quite a deadly firebase which can support the rest of the Tau army and also systematically gun down key enemy units throughout the course of a game.