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I recently joined my college's "Tactical Society" (read RPG, D&D, Magic the Gathering, WH40k, Risk...) and there is one other 'cron player and a couple Tau players. SM, Orks, 'Nids and IG are also represented, but Tau are one of the armies I know very little about. I've researched them and arrived at the following conclusions.
1. Tau suck in CC (but have Kroot to handle that)
2. Tau are a long-range heavy hitting dakka army
3. Stay out of Tau Line-O'-Sight
4. Tau can hurt the 'lith
So what strategies, units and tactics are most effective against these young upstarts?
Dark Lord of the 'Crons
I think I can help here as I play both armies.
generally there are a few things to watch out for, and a few things to no worry about, and a few ways to get it done.
if you are playing against tau, you are undoubtedly going to be facing battlesuits at some point, what you need to watchy out for are the ones with missile pods (surprsingly good at meq killing) but even more dangerous are the fusion/plasma combo squad, at 12 inches these guys will per 3 man squad kill 9 necrons and allow 3 of them no armor save or we'll be back without a res orb. another thing to watch out for is the hammerhead, the regular railgun is deadly, even against the monolith. however, as a cron player you also want to watch out for the ion cannon, as it is a long range meq killer. If he has a skyray dont worry too much, its too difficult to use for the seeker missiles, but he may use the markerlghts on it to aid pathfinders.
Couple of ways to deal with the army.
1. lord w/ warscythe destroyer body veil of darkness and a squad of wraiths. I can guarentee, that this will munch up ANYTHING he has even the tanks, and even his hq with shield drones. Another thing to deny him is his movement, take scarab swarms, not only will these guys be cheaper per wound, but they will, outright win in combat if you are semi lucky, and they are fast!, and easy to hide in cover. One thing that I found to work against them is deepstriking the monolith, did it against a tau's back line took out his hammerhead, warscythed his fusion unit and he couldnt touch it, but watch out for broadsides, you might want to infiltrate some flayed ones to take care of them, or again, the lord with warscythe. just remember,each raigun only has one shot, one shot to take out a monolith, or one necron down, so dont wory too much, they are really vehicle killers, so if you deepstrike the mono, he wont have his favorite target, annnd, he'll won't have that lovely range advantadge. OH, also, the monolith doesnt suffer any extra dice from melta weapons, so even if does get the fusion guns close, still glancing on a 6.
if he has marker lights ( alot) and regular troops, you can easily mow them down with destroyers and immortals, but they will outrange you and they are strong, but the wbb should handle it.
General tau philosophy, is to killl the entire unit and move on, so if you get in his face and remove his ability to tanke out your strong units, or remove his mass amounts of strong firepower, you'll do well
I've played a couple games against Tau, and it's interesting to be on the charge for once.
Necron Warriors can beat up Fire Warriors, it's really wonderful to be able to do.
Wraiths make Tau players crap themselves, wraiths can easily run down any unit they have and rip it to little tiny blue alien shreds.
Tomb Spyders are a little slow, and kinda take it in the teeth from tau firepower, however if you keep them in cover (which isn't terribly hard since they're so short) and have a scarab shield, they can make it in and set to like a thresher.
Immortals and Destroyers ignore fire warrior saves, it's wonderful. Again tau shooting hits hard enough that it can pose a problem, but if you stay at range they don't get enough shots to make it matter.
Tau Vehicles don't have terribly high armor (max 13 on the front of their tanks) so HDs can actually punch through, though small squads and high target priority may see them dead pretty quick.
At the end of the day it comes down to getting into close combat with their specialists, then engaging their line troops at will (which close combat is still great for) but really N. Warriors can go toe-to-toe in the rapid fire game with F. Warriors especially if you take away their marker lights.
(Bah, I totally needed a topic for Arts this week...)
first things first.. welcome...
dont worry abot kroot at all, necrons can beat them in hand to hand too thanks to high saves and the kroot not having a good save at all..
scarabs are fun to use against tau as they can beat fire worriors un in close comba and sheild your crons..
one thing i have to say craig1r is that battle suit plasma rifels dont stop WBB onlt the fusion blaster.. granted they both ignor our saves but they can get up afterwards..
If you have a Necron list, post it, and we can offer specific advice.
In general, though, I gotta second the scarabs. They are fast enough to run down those pesky crisis suits. My first Necron 40k game ever (back in 4th edition) I used a 7-base unit to tie up my opponent's uber-tooled-up Tau commander for nearly the entire game. I'm not sure he even got a shot off!
Now, watch out in 5th. It's much harder to "tarpit" anything anymore, but scarabs should still do it against suits. Aside from that, I've got two words: close combat. Yes, I know, the 'crons aren't known for that, but the Tau REALLY aren't known for it. I'm not kidding. That same game I mentioned above, the opponent charged a 14-warrior squad with his full squad of Kroot, plus a Greater Knarloc (forge world model) which he affectionately named "Dino."
Well, Dino & co. didn't last long. They went down surprisingly fast. Against any other army (except maybe IG) I wouldn't be so daring, but against Tau, yeah, get into cc as fast as possible. This will stop the Tau player from moving and shooting, the two things that he does better than you. If you let him move and shoot, you're dead. It's that simple. Using wraiths (if you have them in your list), scarabs, and a destroyer lord with warscythe are all good ideas.
Also consider units that attack leadership, such as the Deceiver (pricey) or pariahs (possibly MORE pricey) or flayed ones (MUCH cheaper, but not as effective). While the Tau aren't as vulnerable to leadership tests as they are to close combat, they still are more likely to fall than Eldar, marines (both kinds) and even IG, depending on upgrades. A "fear" list is not for beginners, mind you, but it can be VERY effective, especially against leadership-vulnerable armies.
But again, post YOUR list, and I can offer more specific advice.
Okay, (since I don't have the following units: C'Tan, FO or Immortals [going to convert some warriors into 10/10] H-Destroyers, Wraiths, Pariahs, Tomb Spyders) this is my proposed list.
I'm guessing the Normal 1500 points
2 Lords (sadly I bought foot slogging scythe lord)
30 Warriors (3 squads)
15 Scarabs (8/7 split)
I'm planning on DSing the following units: scythe lord, Scarabs, Monolith
Dark Lord of the 'Crons
Or am I better simply turbo boosting the scarabs? I could try DSing a warrior squad by the monolith or simply use the monolith and lord to drop together (avoiding scatter if things work out right) and use the scythe lord to kill me some Crisis suits. With the GoF I even get a shooting attack and the Phase shifter should increase his survivability near all that Tau armor penetration.
Dark Lord of the 'Crons
Yes, tourbo boost with scarabs equals 2+ cover save.
I'm curious how you expect to Deep Strike the lord? Unless it has a VoD it can't do that.
Scarabs should be fine turbo boosting, especially since they ignore terrain while doing so. Having one squad in reserve to deep strike might not necessarily hurt though.
Monolith should be taking a deep strike, as Railguns will tear it off the board like you wouldn't believe. I wouldn't run any warriors in reserve to port through it, you may still lose the thing right off.
Planning to run a lord around alone? That's not really the greatest idea with a foot-lord. They're expensive, slow and don't hit hard enough to go it solo. I'd look at putting it in a unit. Alternatively, fear bomb lists can actually work on Tau since their leadership is so crummy, VoD and Nightmare Shroud could REALLY cause problems for your opponent's firing lines. Also Necron Lords don't really need to run WYSIWYG, so you can equip him as desired.