Level 2: Ferrum Basin
Mars is the Empire's ore world. Terra makes the Sentinels, but Mars makes the metal. Ferrum Basin, a rust-desert basin of iron-oxide sand, was strip-mined for the composite the Lorica is made from. Its rigs are Terran: ore hoppers on tracks, haul gantries, cable-and-winch tether lines that drag loads across the dunes, and storm vents from the atmosphere processors that keep the dust moving. The Basin was a machine, not a settlement. Crews rotated and nobody called it home. That is why it fell quietly. The rigs kept reporting nominal until the haul cables began to move on their own.
What the Nihil did to it
The Nihil came up through the sand, not down from the sky. A seed from the Selene breach reached the Basin by ore transport and was planted under a rig. It did what the Hive does to metal: it veined over the tether lines and processors and turned them into organs. Iron oxide became the Hive's own pigment. Rust is Nihil blood on Mars, the red in everything grown here, and it corrodes Terran plating. The storm vents now carry that rust, so the dust is a weapon. The brood is shaped by the place. It grabs with the tether lines, waits under the dunes and spits from the vents.
The Mars brood
| Kind | Name | Taxonomy line | What it is |
|---|---|---|---|
| grappler | Lash | Tether-caster · Nihilis hamatus | A mid-range biped. A haul cable from its shoulder was grown into a tendril that latches and pulls. |
| burrower | Dredge | Ambush-delver · Nihilis fossor | A melee ambusher grown from the trench-diggers. It lies under the rust-sand and erupts on the nearest Sentinel. The ground trembles first. |
| spitter | Gall | Rust-caster · Nihilis corrodens | A ranged caster with a distended storm-vent organ. It lobs corrosive rust, and each spatter lifts more dust into the storm. |
| ironback | The Crimson Ironback | Node-class · Nihilis ferrugo | The boss of the Basin. |
The Crimson Ironback
The body. A hive node, like the Goliath but a different organism. The Ironback grew from the Basin's heavy ore hauler, a tracked gantry rig with a hopper on its back. The hopper rusted and veined into a shelled, crimson iron-oxide back like a carapace, dense, ridged and the colour of dried blood. The rest of the machine became a big bipedal brawler. The track assembly split into legs, the gantry became shoulders, and the hauler's winch became a bio-tether grapple arm, a grown cable that hooks what it hits and drags it in. It has no face, no mouth and no voice. Like the Goliath, it never speaks.
How it fights. First come rhythmic slam combos. It was a machine with a duty cycle, so it fights in beats, and a Sentinel who learns the beat can step between them. Then the tether pulls: the grown winch fires and reels, and what it catches is dragged under the slam. Last is the rust storm. The node opens its vents and floods the Basin with rust-laden dust that dims the visor. The storm is fed by grown vents scattered across the Basin, which is why cutting them thins it. The shell is armor, not an organ. The tether arm is the soft part.
Defeat line. "Anchor severed. The basin is still." The node is cut from its anchor and the dust settles. Its Latin epithet, ferrugo, means rust.
Objectives
Hold the Rig: an ore rig whose drill, if it spins up, will bore through the node's anchor, so the brood rushes it. Cut the Feeders: the grown vents that pump rust into the storm. Both are Terran tasks on Terran machinery, and the caches they release are sealed drop-ship stores.