Scything Talons
From Exterminatus Manual
The carnifex tyranid genius has massive talons of hardened exoskeleton that it uses to scythe though it's enemies. Short ranged, moderate speed of attack and massively powerful. The screamer killer variant has four of these talons, allowing them to strike four different targets with each swipe. The vennon cannon variant only has two talons, halving the number of targets it can engauge at once.