Carnifex

Overview
The Carnifex, or Carnifex Primus (literally "flesh-maker", Latin for "butcher" or "executioner" ), is a monstrous creature that acts like a living tank for the Tyranid army. They first appeared in Rogue Trader and in their current form for Second Edition of Warhammer.

Description
As Tyranids are constantly evolving their forces, many different variants of the Carnifex exist. However, all Carnifex share some common characteristics: they are very large creatures, standing significantly larger than a man; they have thick carapace, which provide excellent protection from damage, and they frequently use some of the bio-weaponry utilized by the Tyranids. They are comparable to the Space Marine and Ork Dreadnoughts in purpose. Carnifex is a living engine of destruction that is impervious to small arms fire. Can be upgraded to have thornback armor, a barbed strangler, spore cysts, a venom cannon, or to project bio-plasma.

Variants
There are four major variations of Carnifex: the Carnifex Vorantii, the Carnifex Ululare, the Carnifex Arbylis, and the Carnifex Bilius. These are more commonly known as:
 * Thornback: bears enhancements that resemble large spikes or thorns and are used to push through an enemy's lines.
 * Screamer-Killer: the first type of Carnifex encountered by the Imperium. It is known for emitting a piercing shriek before crashing into its foes.
 * Bile-beast: spews acidic fluids onto its foes before attacking in close combat using its huge crab-like claws.
 * Stone-crusher: siege variant Canifex that was originally introduced for Cities of Death, and then modeled and released by Forge world. It is armed with huge wrecking claws, capable of tearing down the thickest of fortifications, a heavier version of a scything tail, and battering rams; used for crashing into enemy ranks, and fortresses. Other sightings of this creature have been seen with a large wrecking-ball looking symbiont.
 * Bio-plasma: The huge plasma ball that can spit from the Carnifex mouth. It was very powerful ability. This effect against group of infranity.