1 Codex: Adeptus Mechanicus
The Adeptus Mechanicus are the keepers and producers of technological know-how for the Imperium of Mankind. It is a position they protect jealously, using their very own standing armies, engines of battle and god-machines. It is within their strength to unleash the most arcane weaponry in the Imperium, and they do so without mercy. Grim processions of troopers stride in ideal unison, every one a worrying fusion of man and machine. Behind them stomp soulless automata, and towering over them are giant walkers. An Adeptus Mechanicus army marching to battle is a sight both terrifying and glorious.