The Tyrannofex is a massive Tyranid Bio-Titan that exists purely to spread destruction to the Hive Fleet's foes. Created for service on the most grueling battlegrounds, the Tyrannofex is clad in a dozen layers of ablative chitinous armour and supported by three pairs of massive legs. It is as unyielding in battle as any war engine constructed of steel or crafted from more conventional technology. The Tyrannofex has the armour and fortitude of a living battle fortress and its bio-weaponry eclipses that of its foes' most powerful main battle tanks in both quantity and destructive potential. Worse, its body houses several breeding chambers, nurturing all manner of ferocious Tyranid organisms that it can unleash onto any enemy foolish enough to come too close. Its main weapon is a massive Bio-Cannon fused with its torso, the largest and most destructive of any of the Tyranid bio-weapons carried by a Bio-Titan. The precise nature of this weapon differs from Tyrannofex to Tyrannofex. Each represents a particular pinnacle of Tyranid bio-weaponry and is as efficient as it is unearthly in its design. The Magos Biologis of the Adeptus Mechanicus speculate that the Tyrannofex, like the Hierophant, was derived from the combined genetic strains of the Tyranid Carnifex and the Dominatrix.
Given its massive size, the Tyrannofex is ungainly and prone to being overwhelmed when engaged in a long melee battle. However, the Tyranid Hive Mind has adapted this biomorph to compensate for this weakness. When the Tyrannofex finds itself in difficulty, it can emit a stress pheromone that attracts other Tyranid bioforms more suited to close combat. Once the primary threat is eradicated, the Tyrannofex can then return to its primary goal of blasting the enemy with its fearsome bio-weaponry.
- Acid Spray - This version of the Tyrannofex's Bio-Cannon stores huge reservoirs of caustic digestive fluids used to break down organic matter at a rapid rate. This acid corrosion is sprayed over the Tyrannofex's victims, melting through their body armour with horrifying ease and reducing its victim to a puddle of liquefied flesh.
- Fleshborer Hive - The fleshborer hive is a seething colony of the very same Tyranid borer beetles found in a Termagant's fleshborer. The fanged creatures stored in the bloated sacs of the hive lay thousands of eggs that hatch and mature at an astonishing rate within the cavernous chambers of the brood nest. Indeed, the fleshborer hive must eject the beetles at regular intervals to prevent the Tyrannofex from bursting apart as a result of the actions of the smaller creatures birthed within it.
- Rupture Cannon - When fired from this version of the Tyrannofex's Bio-Cannon, two different cannonball-sized organic projectiles are launched in quick succession. The first is actually a bloated tick that bursts upon impact, showering the target in an oil-like substance. The second is a seedpod covered in a virtually indestructible biopolymer shell. As the seed smashes the target, it is coated in the viscous remains of the tick. When combined, these inert fluids rapidly dissolve the toughened shell of the seedpod which produces a massive explosion powerful enough to wrench even armoured vehicles inside out.
- Codex Tyranids' (5th Edition), p. 53