Bio-acid/plasma melt through necrodermis

• War in the Museum:

"The lych-captain intercepted it with a perfect vertical slice. Had it been a grenade or shell, he might have scythed through the detonation cap. Instead the spore opened, rotten and steaming. Ropy splashes of bio-acid descended on the phalanx. The lych-captain took the worst of it, tarry ichor covering his chest and face. His metal body screamed as it warped and deformed, the armour plates of his front expanding so quickly it bent him over backward and snapped his spine. The cryptek to Trazyn’s left dashed away, one arm a melting ruin."

• Shield of Baal [Devourer]:

"Their throats were massive sacs of swinging flesh. The creatures stood nearly as tall as the ravine itself. Anrakyr struggled to divine their purpose, what the tyranids meant to accomplish. He understood, seconds before it was too late. ‘Block the mouth! Kill the creatures!’ he screamed. The remaining three monoliths arced down, anti-gravitic fields straining as they crashed into the ground, blocking the monstrous beasts from Anrakyr’s view. A great retching sound filtered through to the necrons, then a steaming hiss as viscous liquid spilled forth. Smoke began to rise from the monoliths almost immediately. A tide of bio-acid spilled around the flanks of the slab-sided constructs, filling the defile in a great, hissing flood. Entire phalanxes of warriors dissolved beneath the slurry, denuded down to nothing."

​ • Shield of Baal [Exterminatus]:

"Both Space Marines and Necrons learned to be wary of the lumbering Exocrines of the Fabricae District. Neither ceramite power armour nor living metal were proof against their bio-plasmic cannons."