(Note I'd really like some suggestion on names here.)
Forge Atagninak focuses on the design of machine spirits and communes with them. The legion sees the boundary between the world of the living, the world of the dead, and the noosphere as porous, with powerful cogitators playing host to the spirits of the ancestors. The Magi of Ataginak conceptualize the person as containing several non-physical parts, principly the Motive Force, the Nous, the Animus, and the Kavak. When a magos dies, their Forge-Clan hosts a funerary feast. The Nous is uploaded into the planetary network, while the Motive Force is kept within the community by donating the cybernetics of the deceased to the attendees. These ritual feasts are part of the core of practice on Ataginak, with a key role being given to the Speakers, a special order consisting of Datasmiths, Cyberneticae, and Titan Principes. The Speaker is linked to the network and allows the Machine Spirits to speak through them.
The ruling Synod is made of the heads of each of the Forge-Clans, lead by the High Speaker, who serves as a conduit for the Machine Spirits and the Ancestors, and it is also the Speakers who summon spirits from the cogitators. This results in the trace of Nous being given to products of the forge, resulting in better performance.
While Ataginak is best known for their cybernetica, their data looms are of very high quality, their data djinn are legendary, and their targeting matrices are some of the best in the imperium. However their machine spirits can prove difficult for others to use, usually becoming petulant when not treated properly, particularly since few off Ataginak are willing to perform the dances much less allow a Machine Spirit to speak through them. In some cases, an unhappy Spirit will possess servitors and machines, requiring extensive feasting or a techorcism. Such events have lead to occasional charges of Silica Animus, but the argument that the portion of the Ancestral Nous each machine possesses provides the requisite human factor has been successful thus far. Cynics have noted that the reason may have less to do with the soundness of the argument than with the questions that denying that doctrine would raise about heavily augmented Magi. Such a stance also allows Orthodox datasmiths to explain otherwise troublesome behaviors of Ataginak Spirits without acknowledging the theory or praxis of their creators. The Orthodox allege that the theory of mind and gnosology of the Ataginak Magi is, in fact, an attribution error; the heterodox rites of Ataginak work because the Nous of the deceased inside expect them to. Regardless of the facts, this compromise has worked for both parties.
Legio Funebris: The Tomb Speakers
The Titans of Ataginak are understood as vessels for the Ancestors and Machine Spirits. This understanding of the Titan’s spirit leads to a different relationship with the Engines than is typical elsewhere in the Imperium. Contrary to the usual procedure where a Princeps subdues and constrains the raw fury of the Engine’s spirit, the Princepes of Funebris commune with them, even speaking in the plural for the duration of the bonding. They speak of being surrounded by the Ancestors and the Spirits, who offer advice, but also aid in commanding the Motive Force harnessed in the War Engine’s Animus. The result is a hybrid soul. By temprament, Funebris is highly aggressive, but controlled. They stride the battlefield like the gods of death, neither hurried nor aimless, but driven by terrible purpose.
In terms of engines, the legio is well balanced, though there is a distinct preference for auspex jamming when possible, with the Dominus Maniple a perennial favorite.
House Anwyn (or something of that nature)
Legio Funebris' oathbound house. Even when the knights themselves are beyond repair, the Thrones are recovered and inserted in new chasses. The house's nobles are incredibly reclusive because DUH DUH DUH!!! They're already dead!! The throne mechanicums are so old that they have created gestalt personalities that largely overpower living pilots put inside or run the Knights requiring only a servitor as an interface. As a result, the Knights fight with a reckless abandon. They don't know they're dead, and in fact, the Sacristans spend a great deal of time and effort making dreams for the machine spirits so they don't remember that they're dead. (And so that way they don't get caught for possible Silica Animus)
Anyway, they don't know they're dead, but they're aware that they've come back from what should have been many a terminal encounter. Thing is, as long as the Black Box can be recovered or the backups can be downloaded into a new throne, they're good to go, so the "pilots" just assume that the Omnissiah watches over them and brings them back from the edge again and again.
A note on how things go wrong for them:
Given their different approach to AI, they tend not to make the same mistakes as other forges with regard to Silica Animus or the Warp. Instead, the machine spirits here have problems related to the way their conceptualized. They're more likely to become sullen, petulant, or offended, if not offered the proper rituals. The Cybernetica Cortecies are less likely to go omnicidal and attempt to exterminate humanity, but are rather likely to behave more like the animals they're based upon and may emote like a dog or horse. The Knights of House Anwynn are less likely to feel the warp overtaking them and more likely to freak out because they're having flashbacks and realizing that they're actually dead. This may cause some anger and resentment. So they've got problems with their technology the same as other forges, it's just that they take a bit of a different form.