This article, by hierophant99, explains why and how to use Carnifexes. Enjoy!

Carnifex by ajf798
Why Carnifexes don't suck
Do Carnifexes suck in the new Tyranid Codex? Definetely not.
Most Tyranid players use Trygons, Mawlocs and Tyrannofexes, instead of the poor old Carnifex.
Players say that it costs far too many points and that the other heavy support choices are far more effective.
But fortunately for the Carnifex, those harga kompor gas cosmos
statements aren't right. Carnifexes present several distinct
advantages that no other units in Codex have.
First off is their ability to form squads. Many powerful close combat units won't be afraid of charging a
Trygon, since they will probably be able to take off all six of its wounds and survive its six strength 6 attacks.
But those same units will be much less prepared to charge a unit of Carnifexes with an amazing eight or
more wounds and eight or more strength 9 montrous creature attacks! Plus, once a unit is stuck in combat
with a squad of Carnifexes, it will almost always die or sustain massive casualties. A brood of Carnifexes is
ridiculously deadly and hard to kill. Also, in squads, Carnifexes will be less likely to give up Kill-points to
your opponent. Eight wounds are harder for your opponent to inflict than four.
Second of all, Carnifexes have a ridiculously high strength value of 9. No other unit in the Codex has a
strength value even close to that They can even have a strength of 10, if charging with Adrenal Glands.
Their high strength lets them rip apart other monstrous creatures, high toughness foes and vehicles with
shocking ease. Plus, Carnifexes can Instant-kill multi-wounded infantry, like Ork Nobs, and Independant
Characters, like Space Marine Captains.
Third of all, Carnifexes are the best option in the entire Tyranid Codex for flushing enemies out of cover.
With Frag Spines, Adrenal glands and their Living Battering Ram rule, Carnifexes can charge foes in cover,
and almost always strike first with their five strength 10, armour-ignoring attacks, each!
Fourth of all, a Carnifex is cheaper than a Trygon, Mawloc or Tyrannofex, allowing you to spend more points
elsewhere in your army!
How to field Carnifexes
If you read the first section of this article, you know that Carnifexes should always be fielded in squads.
If you want a lone monstrous creature, you're better off with a Trygon. Even a single Deep-striking
Carnifex is nothing compared to a unit of them.
Carnifexes should always kompor gas quantum
take two pairs of Scything Talons. The ability for a monstrous creature with four
attacks and strength 9 to always re-roll to hit is simply amazing. Heavy weapons are best used by other
units in the Codex and Crushing claws negate the great Living Battering Ram rule.
In terms of upgrades, Adrenal glands is the most useful one. On the charge, it gives Carnifexes the
strength to Instant-kill toughness 5 characters, like Ork Warbosses, a wonderfully high initiative of 4 and
even more raw smashing power. Frag spines are nice, allowing Carnifexes to easily massacre enemies
hiding in cover, even if they're Space Marine Terminators! Toxin sacs totally suck on Carnifexes.
Regeneration is too pricy and is only effective if you roll a heck of a lot of sixes. Bio-Plasma is deadly,
but is very innaccurate and risks scattering back onto the Carnifexes. Also, Bio-Plasma is only really
effective against Space Marine Terminators.
So, the best way to field Carnifexes is in squads of two of three, with each Carnifex having two pairs of Scything talons,
Adrenal glands and Frag spines.
How to use Carnifexes
Carnifexes are incredibly powerful, and most opponents know it. Expect almost every lascannon, plasma
weapon or other high strength gun in your enemy's army to shoot at Carnifexes. To actually get into
combat, where they excel, Carnifexes will need cover. If there isn't enough regular cover on the table,
try sheilding your Carnifexes with another tough monstrous creature unit, preferably a Hive Tyrant with
Tyrant Guard. Such a unit will give your Carnifex squads cover saves, or will soak up a lot of firepower.
A screening monstrous creature unit also makes sure that your Carnifexes get to charge (and use their
+3 initiative), instead of getting charged (and having to be stuck with initiative 1).
Your Carnifexes should never charge with your troops. If you ever charge a Carnifex squad and a low-toughness
infantry unit into an enemy squad, that enemy squad will target the infantry unit and might cause tons of
casualties, which will force the Carnifexes to take many Fearless saves. This way, even Space Marine
Tactical might do some serious damage to your ultra-tough Carnifexes. So, always keep your Carnifex
squads, and all of your other monstrous creatures, from assaulting alongside more fragile infantry.
Main targets for Carnifex squads are elite or multi-wounded infantry, such as Eldar Wraithguard, Ork Nobz,
Independant Characters, vehicles and high-toughness foes, such as enemy monstrous creatures.
Carnifexes can easily pulverize all of these.
A unit that Carnifexes should watch out for are basic infantry. These will either tarpit a Carnifex squad
for a very long time, or will murder it slowly, with power fists, toxin sacs or other such equipment. Save
basic infantry for your own infantry units to kill.