The carnifex is the Hive Mind's answer to any obstacle too solid for lesser broods to simply overrun. Massive beyond the scale of a human tank, its body is a dense architecture of reinforced chitin plate and corded muscle, purpose-grown to absorb punishment that would annihilate lighter bio-forms while its bladed limbs and crushing claws reduce bunkers, vehicles, and defensive lines to wreckage.
Despite its brute strength, the carnifex is not a mindless battering ram. Its exact configuration of weapon-limbs is tailored before birth to the specific threat it is meant to counter, meaning a single engagement might see one carnifex bred for tearing open armored hulls fighting alongside another optimized purely for close-range slaughter of infantry, both grown from the same template but shaped by different tactical demands.
Commanders who have faced carnifex broods learn quickly that conventional anti-armor tactics often fail against a target that can shrug off wounds no war machine should survive and simply keep advancing, driven forward by a will that feels no pain and recognizes no reason to retreat.