Necrotic Mutox
T2 CS16 07
Also known as
Builder's Breath, Rust Gas
Everything Organic
First Introduced
Truart: They're gone! And what remains in their stead? Sand? No...rust!
Karras: Indeed, 'tis very much like rust, and harmless once settled.

The Necrotic Mutox, also known and nicknamed as 'the rust gas', was the deadly substance that was contained in the gas canister, planted inside the Masked Servants. This gas was accidentally discovered by Karras, the leader and spiritual guide of the Mechanists during The Metal Age, and took it as a Master Builder's gift to accomplish his plan.

Chemical PropertiesEdit

The gas is a red vapour that consumes anything organic it touches; the reaction produces inert powder, resembling rust, and additional gas (suggesting that it is an organically derived compound). Although it quickly breaks down when exposed to atmospheric conditions, the self-propagating reaction can be sustained until the organic material is depleted. The degraded "safe" form appears as a very dense fog of darker red which settles on the ground.

  • Necrotic Mutox, as seen when coming out of the Masked Servant's Cultivator.
  • Rust Gas canister.
  • The inert secondary form, following a reaction.


Necrotic Mutox + organic matter --> simil-rust material + Necrotic Mutox

Use in Karras's PlanEdit

Soon all will be blessed with the breath of The Builder: the Necrotic Mutox that I created. And all the souls--the rich that spurned me, the City Watch that betrayed me, the loathsome Pagans, the mindless commoners, even the loyal followers of Karras, all!--all will receive the blessing and the cleansing. But will they raise up their arms and praise Karras as the vapors make them pure? Nay! They will wail and scream--most ungrateful!
  — One of Karras' speeches on the loudspeakers in Soulforge Cathedral

During the Metal Age, Karras tried to destroy all organic life in the City, and possibly a large surrounding area, in order to create his Builder's Paradise. To this end, he turned street scum and criminals into the Masked Servants.[1] He inserted a device, called a Cultivator (which rapidly propagates the Rust Gas), into every mask. Then, the Servants were gifted to the homes of nobles with large gardens. At the chosen time Karras would send them a signal, using the Guiding Beacon, to release the gas. The gas would consume all nearby organic matter and, by a chain reaction, produce a cloud large enough to envelop the entire city, obliterating all living things. However, Karras's plot was stopped by Garrett, with assistance from Viktoria and the Pagans. Viktoria gave her life at Soulforge Cathedral to fill the area with vines and plant matter, sufficient to support the same chain-reaction and kill Karras. In his preparations, Karras had fitted Soulforge with pneumatic seals to protect him from the gas.[2] When he gave the signal to release it, unaware that Garrett had brought the Servants back to Soulforge, the reaction was trapped within, and the City spared.[3]


  1. T2 Sound Folder: Karras
  2. T2 B16
  3. T2 CS16