This guide comes almost entirely from personal experience, as my main opponent plays Black Templars. To begin, I will outline the strengths of the Black Templars:

Marines- as Space Marines, the Black Templars will enjoy S4, T4, and a 3+ save. In addition they will have a high leadership.

Close Combat- even the basic Crusader Squad has access to pistols and combat weapons as well as upgrades like power weapons, flamers, and power fists. All of them have a WS and I of 4. Their characters and specialist troops are even more dangerous.

Armoured support- the Black Templars have access to some of the scariest tanks in the game.

Then they have their weaknesses:

Righteous Zeal- while this can be viewed as one of their strengths against most armies, it will force the Templars to move out of cover and into assault range.

Fearless- Black Templars are Fearless as long as they’re in Close Combat. Outnumber them and force them to take armour saves for the No Retreat! rule.

Shooting- the Templars do not have devastator squads or any real form of concentrated firepower besides massed bolters and tank-mounted guns. Beware of a Land Raider Crusader though. The Crusader is the ultimate Tactical Squad-in-a-box. It can wade through most of your troops with impunity.

In order to fight this army, the ideal solution would be to field pure heavy weaponry. However, as Tyranids, we do not have that kind of firepower. Instead, we must fight them on their terms; close combat.

In order to defeat them in close combat, we must maximize our own close combat ability while neutralizing their shooting capability. Fortunately, it is not that hard to surpass them in close combat as long as it is possible to get into close combat. The way to do this is to field very fast-moving troops. This means that the Troops slots will be filled mainly with Hormagaunts. Another viable option is to use Genestealers; while lacking the 12” charge of the Hormagaunts, they still have Fleet of Claw. Genestealers will kill even the HQs of a Templar army with ease. Unfortunately they will also attract enough firepower to level an entire city block. Be sure to give your Genestealers extended carapace to help them survive longer. Also useful in this role are Raveners, Lictors, Broodlords, and leaping Warriors. Make sure that Hormagaunts and Warriors have Adrenal Glands so they strike first against the Templars.

The other way to get into close combat quickly is to use wings. A winged Hive Tyrant is invaluable, as it can move 12” AND fill up the mandatory HQ slot AND provide synapse to the swarms of Hormagaunts. Give the Tyrant Warp Field to improve its durability. Then, of coarse we have the Gargoyles. Gargoyles will be best at neutralizing Land Speeders and Assault Squads intent on spoiling your plans by sneaking around and attacking your shooting units.

This brings me to my next point of shooting. While Tyranids are nearly invincible in close combat, there are some units that you either can’t reach or simply do not want to mess with. Against these units you will have to rely on Tyranid shooting. The best units to use for your shooting are:

Carnifexs- can carry and fire two weapons. Use this to your advantage by taking either a pair of twin-linked Devourers (for an Elite ‘Fex) or a Barbed Strangler and Venom Cannon. While some people don’t like to have those two weapons together “because Barbed Stranglers are for infantry and Venom Cannons are for vehicles”, consider this: A Barbed Strangler has S8 on a Carnifex. This means that it is the only weapon in the Tyranid army which can reliably inflict penetrating hits on vehicles. Also, the Venom Cannon gets 2 shots when you put it on a Carnifex, so it can kill some infantry as well.

Hive Tyrants- share the advantages of the Carnifex in their ability to carry and fire two weapons. Either use double Twin-Linked Devourers (getting 12 shots!), a Venom Cannon + the weapon of your choice (the second weapon will only be good for killing infantry, or a close combat weapon), or double Scything Talons and Warp Blast. In addition, you will want to give it a Tyrant Guard or two to protect it from Lascannons and Assault Cannons.

The Winged Tyrant can also be armed with double Twin-Linked Devourers for a mobile firebase.

Warriors- can use Deathspitters or Devourers to good effect in units of 5+, especially when combined with Toxin Sacs. In addition, you may want to invest in a Venom Cannon for the additional range.

Biovores- buy Bio-Acid Mines for these guys. 2D6 armour penetration AND AP3! Don’t let the low strength scare you. You have a better chance of killing them by rolling a 5+ then you have of killing them with a roll of 4+ followed by failed armour save.

One last note on the Barbed Strangler; it is very effective against the Templars because of its pinning ability. Pinning them will prevent them from moving, shooting, assaulting, or using Righteous Zeal. Just don’t fire if you’re hoping for them to use Righteous Zeal.

And that just about wraps it up.