The chassis of a conquered heavy machine, split at the welds and rebuilt by parasite tissue into a ranged corrosion siege unit. It walks to the edge of your range, plants, and holds — you won't stagger it, you won't knock it back. Then the bile lance opens up: a sustained jet of toxic-green corrosion from a sac fused into the engine cavity, eating through tower armor and fortification walls from a distance. It doesn't chase. It doesn't care about you. It just grinds your structures to slag until you're forced to leave cover and come to it. Often fielded with a Graft-Breacher — the Breacher opens the gap, the Rot-Engine keeps it open.
