I was really sleepy last night while writing the 3rd part of this series and had to stop before I could finish. This part is a continuation of Part III.
Mech armies are very popular now and have many advantages. Many believe mech IG is currently the best army and I concur. If you are playing mech IG then you are in the driver's seat. If you aren't then you need to design your army to have all the right tools to beat mech IG. Mech SM is also another strong army and SM players seem to have their niche to win consistently. Both mech IG & SM armies have excellent psychic defense in the psychic hood. While the Librarian is no longer a potent assault unit the Librarian has access to several powerful psychic abilities such as Null Zone which makes their army more of an offensive threat. The Librarian with Null Zone is now a staple choice in many SM armies. The Inquisitor with Mystics is also a staple choice for many IG armies. The Mystics can be countered through deployment though.
So I am not going to delve into tactics & strategies for mechanized armies, rather I am going to focus on how to beat these armies. Mech armies are often composed of MSU (many small units). Therefore, missions that use killpoints are an inherent weakness to these types of armies. It's important that you support the use of unmodified killpoints in tournaments where you play so you can take advantage of this weakness in mech armies. Deployment is also another excellent tool to win against mech armies. If you have enough of the right units that can either infiltrate or outflank then you can deploy in such a manner that mech armies cannot keep away from your army. Basically you want to deny mech armies from lots of prolonged rounds of shooting. To acheive this goal you must force them to move as they cannot shoot as much when they move.
I have posted some Tyranid armies here on the blog that were explicitly designed to beat mech armies. Let's first take a look at Tyranids. Personally I feel that Tyranids have all the right units to consistently beat mech:
Yrmygal genestealers - Deploy them in the center of the table so they act as the hammer to your anvil. They come in and can fleet into an assault the same turn. These elite genestealers should multi charge several enemy units BUT don't make the mistake of assaulting so many enemy units that you spread them too thin.
Genestealers - These units should generally outflank and they are your anvil. You want to hit the opponent on both flanks and charge them up the middle with the Yrmygal genestealers. The enemy is surrounded and has no place to run away. Keep the enemy moving such that you corral them and pack them in tight. This tactic will help you to pull off more multi charges in the latter phases of the game.
Hiveguard - These units are there to shoot transports and absorb some enemy shooting. Even though Hiveguard are T6 and multi wound units concentrated fire from the enemy can quickly blow them off the table. I would drop them in mycetic spores so they can come in close to the enemy line and be in range to shoot. It's critical that they wreck/destroy some transports early in the game so you can slow down the enemy mech and overrun the squads that fallout. Don't waste shots targeting landraiders and other tanks with AV14 facing them, this is very low odds and the best you can do is glance versus AV14 with S8.
Zoanthropes - This is my favorite unit for shooting enemy armor and these units should be deployed via mycetic spores to take full advantage of their S10 AP1 lance. The major drawback to Zoanthropes is enemy psychic defense in the form of psychic hoods. I still prefer Zoanthropes over Hiveguard due to their lance shooting attack. You will need to run at least two Zoanthropes per unit but three is definitely a lot better. Multiple Zoanthropes per unit means you have much better odds of being able to get past the enemy psychic hoods and penetrate their vehicles.
Trygon Prime - These units can deepstrike and have 12 S5 shots. You want to deploy them such that you can shoot against side armor versus chimeras. Versus rhinos it doesn't really matter if you shoot at front or side armor, as it's all the same (AV11). Trygons are very fast since they can fleet so they are also excellent at assaulting vehicles if you can keep them alive long enough after they arrive via deepstrike. What you want to do is saturate the table with your units so that the opponent has to make tough decisions as to what to shoot, thus taking some heat off of your Trygons. Personally I think both adrenal glands and regeneration are must have options for Trygons. They have six wounds so there is a good chance you can regenerate some of their lost wounds. Adrenal glands (furious charge) gives your Trygons the edge versus strong enemy assault units. Obviously you don't want to charge a squad of assault terminators with thunderhammers and stormshields! Upgrading to Prime doubles your number of shooting attacks plus it also let's you spread out your own psychic defense - Shadows in hte Warp (SitW).
Flyrants - While the Hive Tyrant is very expensive this unit brings a lot to the table. If you build him right the Flyrant is going to cost up to 300 points. Here are the options I take - wings, 2x twin linked devourers with Brainleech ammo, Hive Commander & adrenal glands. The pair of twin linked devourers with Brainleech ammo combined with wings (deepstrking) is a huge advantage - basically you have 12 S6 shots that can all be rerolled to hit. The Flyrant equipped as such is excellent at popping transports and again with the ability to deepstrike you should be able to shoot at the side armor of chimeras. Hive Commander gives you +1 for your reserves which is a huge benefit if you build an army such as I have described that starts off the table, everything starts coming in from reserves on turn 2. This ties in directly with my strategy to saturate the table as quickly as possible, forcing your opponent to make tough decisions in regards to what he targets with his shooting attacks. Again you are spreading out your psychic defense SitW. To me there is no reason for the Flyrant to engage in assault as quickly as possible. The Flyrant has more than twice as many shooting attacks as compared to close combat attacks. Take full advantage of the shooting during the beginning through midgame. Note however the Flyrant is excellent for throwing into a quick assault early in the game to help another unit finish off an enemy unit, you destroy the unit on the charge then are free again to continue shooting.
Broodlords - To me adding a couple of Broodlords to your army is a wise choice. They can absorb some wounds to keep a unit of genestealers alive plus they also help spread out your psychic defense SitW. They also add to your offense during assaults and are good for focusing on enemy HQ. I don't take any options for my Broodlords, they are fine as is. Genestealers in general don't really need any upgrades and if you run large units those options quickly add up.
DoM - We will have to wait and see if GW FAQs this unit's Spirit Leech power affects embarked units. If it turns out that it does then this unit will be very effective against mech and will become a staple choice in Tyranid armies. I have seen the DoM take down Wraithlords the turn it arrives... the DoM is very scary.
So these are the main units I run to counter mech, in particular mech IG. Its still going to be a tough battle versus a solid opponent. They can drop ordnance that ignores cover and destroys a huge squad of genestealers with one shot. Remember to keep all your models in a unit all spread out 2" apart, this is the best defense versus ordnance in general. You will have to work your way through the blobs of guardsmen and chimeras to reach their ordnance. So be it. Keeping the enemy constantly moving to decrease their shooting and corral them into a tight cluster so you can multi charge them during mid to endgame. You are both playing a game of constant attrition trying to remove more blocks of enemy units faster than your opponent. All mech armies suffer from what I refer to as the inevitable collaspe if you can keep pressing them hard enough. Mech armies want to sit back through the first two stages of the game then move their transports onto objectives during the endgame. If you can quickly destroy enough of their transports early on they will lose their mobility, that's a big part of what it's really about!
Next I will focus on how to beat other mech armies such as Space Marines. Keep in mind that many of the tactics and strategies I have discussed above apply to beating any mech army. The goal is to design one army that is balanced and can beat any other army. If you focus solely upon beating mech armies then you can run into huge problems versus hordes and other infantry based units. The type of Tyranid army I have described above is very fast (infiltrate, outflank, deepstrike, wings & fleet). The army also inherently excels in close combat but has a limited amount of shooting so it's quite prudent that you carefully decide how you go about selecting which enemy units you will target with your shooting. A little bit of shooting can go a long way if you are wise. It's very important to apply focused fire and go with high odds in your favor. While the Zoanthrope's lance shooing attack is the best attack versus high armor such as landraiders you obviously don't want to waste these shots versus blobs of infantry. Focus on destroying the opponent's transports first, it's one of the big keys to beating mech.