Deus Machina
Deus Machina are a particular type of mecha, often but not always humanoid, that make use of Mythos sorcery to fuel devastating attacks and incredible defenses. Owing to the method of their construction, Deus Machina possess some degree of self-awareness, but the structures of their mind make it almost impossible to communicate with them. The power of a Grimoire is required to bridge the gap between mortal and machine and activate the machine in the first place, a requirement that makes Deus Machina even rarer than their component parts.
The most recent known use of Deus Machina took place in the Arkham Event in the late 1920's, when the Hadou Group-- a powerful, world-spanning financial organization-- faced off against the infamous cabal of sinister Mythos sorcerers known as the Black Lodge. Demonbane, the first and only Deus Machina created solely by Human hands, was the Hadou Group's secret weapon: sporting both conventional and esoteric weaponry, and built to a generally anthropomorphic standard. While powerful of its own accord, its fighting strength was increased dramatically by the presence of Al-Azif as the Grimoire responsible for its activation, allowing its pilot the ability to field both the (un)conventional weaponry built into Demonbane and Al-Azif's own formidable destructive and defensive powers. Ultimately, Demonbane and the other Black Lodge Deus Machina were either destroyed during the conflict or cast into the depths of space, and none are known to exist on Earth at this point in time.
The success of Demonbane has demonstrated that mortal-made Deus Machina are viable weapons against the Mythos. The problems in implementing them on a wider scale are threefold. As with all giant robots, one must be able to make them combat-viable against conventional forces, and much of the expertise used to create Demonbane has since either been lost or dispersed in the wake of the Arkham Event. Secondly, a Deus Machina requires someone who is capable and talented with Mythos sorcery; owing to the relative dangers of studying the Mythos and scarcity of the material, few groups capable of producing a Deus Machina are willing to trust a potential rogue outside of their ranks. Thirdly, even the most powerful sorcerer cannot interface with a Deus Machina in absence of a Grimoire. While almost any Grimoire-- or even fragments of a very powerful Grimoire, in a pinch-- can be used to power a Deus Machina, going with a weak one means that the Deus Machina will be comparatively underpowered and completely reliant on its own built-in weaponry.
Given the above, organizations inclined to field mecha find that it is less expensive and more reliable to use more conventional weaponry and mecha than go to the trouble of constructing a Deus Machina. Pilots are uncommon, and worthwhile Grimoires are almost impossible to find. Were an organization to find a willing sorcerer and Grimoire, though, they could well find themselves with a weapon capable of rivalling even the theoretical EVANGELION projects discussed in the late 1990's.
