Tau as Allies

Pretty simple idea: how to make Tau into an Ally force?

It's actually harder than it looks. Unless you're using 1999+1 you're going to be in trouble. Their troops are bad enough that no matter what you do with them you'll be wasting points. And, if you want to buff them, you have to get an Ethereal or a Fireblade which hurts the Ally slot because you can't take Signature Systems like a Commander can. The rest of the army has a lot of trouble standing on it's own so now you've got a much harder question than at the beginning.




Here's really the only idea I've had:

HQ
Commander, Puretide, Multi-Spectrum, TL Flamer (130)
Troops
Kroot, 2 Hounds, Snipers (80)
Heavy Support
3 Broadsides, Missile Fists, Velocity Tracker (255)

So in total this Ally costs you 465 points and it's the cheapest I can get it while still being effective. You might spend money on the broadsides and commander to get them drones (missile and shield, respectively) but once you start doing that you're probably adding ~50-100 extra points. Like I said, if you aren't at 2000 points these Tau get really expensive.

But what does this ally do for you? Simply enough it's an anti-vehicle anti-flyer backup. It frees the rest of your army to go anti-blobs while hopefully giving your opponents target priority issues. Broadsides with missiles are really good at anti-air and can even snipe down the nefarious Heldrake in 1 round if the Commander joins them with Puretide (allowing re-rolls of failed glances). The big issue is that these guys are very expensive and don't have much safety versus assault. A good idea would be to put them in an Imperial Bastion to prevent them getting smoked. I thought about dropping skyfire from 1 and keeping the Railrifle but really the only edge that gives you is coolness factor. You have 1 shot at 1 higher strength and low AP. What's better at killing a sample vehicle like a Rhino?

Railrifle: 3/4 to hit (re-rolls) and 3+ to wound means you only have a 50/50 chance of even hitting the vehicle on side or front armor. Since you need 4+ to pen you have 37.5% of getting a pen. With AP1 you have a +2 on the vehicle damage table which gives you a 4+ to destroy the vehicle. So overall you have an ~1/5 chance of killing it.

Missile Fists: 3/4 to hit with 4 shots, 4+ to glance or pen means that on average you will kill the vehicle. The chance of glancing to death is much higher than the Railrifle's chance of killing. So even against light vehicle the Railrifle sucks. The only benefit of the railrifle over the Missile fists is ability to wound AV14. Which it is bad at. So literally no reason to take it.

So now you have another question to ask: can you do this with other people cheaper. And the answer is yes. Which sucks. Here's an example:

Dark Angels
HQ
Librarian, Prescience[Divination Primaris] (65)
Troops
Space Marines (70)
Dedicated Transport: Razorback, TL Lascannon (75)
Heavy Support
Devastator Squad, 4 Missile Launchers, Flakk (170)
Dedicated Transport: Razorback, TL Lascannon (75)

10 points cheaper. Gives you less anti-air but a lot more anti-vehicle with 2 TL lascannons on vehicles and 4 re-roll missile launchers. It's not even that well-crafted and it still does the job. Also you now have strict contenders against anti-AV 14 and AV13.

Let's see how well a TL Lascannon does against Rhinos:

1 shot, 8/9 to hit (re-rolls) and 2+ to glance means that ~60% of the time you'll get a penetrating hit leaving you with about 20% to blow it up. Almost exactly the same result as the Railrifle but you'll hit about 20% more often and with the ability to do actual damage versus AV13/14.

The Flakk Missiles are actually less effective versus aircraft than the Missile fists. The Flakk Missiles though are as effective at bringing down HP2 flyers so you've got an even tradoff. You have much better anti-light vehicle though with Krak Missiles and a little bit of blob killing with the multiple blast templates so the weapons are pretty tied in effectiveness in my opinion (as long as you have the Prescience Librarian in the squad).

For the 255 you're spending on the Broadsides you're picking up a unit that reaaaaally needs a screen because simple templates can wipe the unit without any effort. They're also exceptionally weak to charges and can get tied up for the whole game. You need to probably spend an additional 50-75 points to get an Aegis Defense Line or Imperial Bastion (which you could then use to get a Quad-gun, an arguably cheaper investment overall that you can put people on)

Other than Dark Angels though the lack of anti-air is only really countered in lists by the inclusion of Quad-Guns. Without those the only answer to anti-air is ignoring it as Flakk missiles without re-roll are really bad. With a full 4 man squad you'll average 7 glances/pens in a 5 turn game..but only against AV11)

Now with other armies that are lacking anti-air the question is: Do they have compensation for it? Sorta.

Quad-gun is the obvious solution. For a lot of marine codexes you can also take Rifleman dreads since there isn't much competition in the Elites slot. Grey knights probably don't have much against it actually as Dreads are in the Heavy Support slot for them which will be taken by Dreadknights whom are not effective versus Flyers. They do have their own flyers, however, who can get TL Lascannons for free to shoot down other flyers. Not exceptionally dangerous for Heldrakes but can shoot down a lot of other flyers on their own between that and TL Multi-melta (both free). Eldar have very little ability to take down aircraft and benefit from Tau allies the most. Necron have a huge airforce usually and thus can tango a bit with others. With Tyranids, CSM and Daemons you have lots of Flying Monstrous creatures and the oft mentioned Heldrake is good at downing other flyers so they don't really need it much either. So in the end who is left? Sisters of Battle and Eldar are the only ones without really any anti-air capability and thus benefit heavily from Tau. But wait a minute: Sisters are actually Desperate Allies to Tau. Guess they can't help there. Also I didn't mention IG but they really have no need for anti-air help when they can take un-killable blobs and 9(!) Vendettas to shoot down other Flyers.

This leads you to another question: I don't play Eldar what use are Tau to me? The answer I keep arriving at is none. They don't have enough to offer in just 1 slot for a useful ally. The only other things I can think of are suicide Crisis Suits with a Kroot squad for camping.

Example
HQ 
Commander, TL Flamer, Burst Cannon (105)
Troops
Kroot (60)
Elites
Crisis Suit, 2 Extra, TL Flamer, Flamer (111)

Now currently RAW this is not illegal. You're dropping a 216 point unit with 4 TL Flamers and 3 extra Flamers and a Burst Cannon. This squad is strictly for removing a blob from the map. Deep-strike them in and watch them annihilate a blob before getting counter-fired and wiped. You may be able to get the whole squad off twice which would be miraculous but really it's just a simple 'rock' for the blob 'paper'. The whole shebang costs 276 points leaving you with 1724 for your army (or 1474 at 1750) which is really nice but the squad it kinda useless without a good target nor against semi-mech.

Conclusion
I have trouble seeing Tau as an ally and really the only effective build with Tau is the Triptide build in the previous post. It's disappointed how much long-range fire they've lost and how they're now Codex: Missiles. They lost a lot as an ally with the nerf to Railgun, so much so that I'm having trouble seeing the point of taking them.

Tau have a lot of issues with slot management, troops and weight of fire. Which is ridiculous for a codex based purely on shooting.