Green, insectoid, blind (their heightened perceptive abilities negate the need for sight), mostly bipedal (with exceptions), physical appearance heavily dependent on function. For example, Kyrozch scout drones are small (about three feet tall) and very fast, whereas Kyrozch leader drones are much larger (the size of a small house), tougher, and stronger. Their exoskeletons are formed from a matrix of chitin, keratin-like protein, carbon nanotubes, and notum; the notum gives the otherwise greenish-brown "skin" its characteristic sinister, radioactive green appearance, and also gives most Kyrozch drones, especially leader drones, an appearance of crackling with energy.
Their genetic material differs in building blocks from that of terrestrial life forms, and thus much of the biomatter that comprises their bodies is alien in nature (i.e. no terrestrial organism produces comparable matter).
Their extensive knowledge of biotechnology allows them to graft weapons and tools directly to their bodies, fueled by their notum-rich blood; their thirst for the material stems from the fact that they rely on it as a primary source of energy for absolutely everything, to the point where they are physically dependent on it - it is both their drug and their petroleum. Like most scientists, they believe (insomuch as they have the capability for belief) that notum is a resource created at the beginning of time in finite, normally very small, quantities. A large source of notum, like that on Rubi-Ka, would mean salvation for their kind for potentially millions of years - perhaps enough time to rebuild the civilization they lost around when the Prophecy was forged (but you don't know about that yet).
Hand to hand, it is extraordinarily difficult for a human to defeat a Kyrozch drone. Even an otherwise unarmed Kyrozch scout drone has fearsome, razor-sharp energy claws that will make short work of practically any material. The most commonly accepted tactic for a human force to defeat a Kyrozch force is concentrated, massed firepower at medium to long distances, supported by heavy weaponry.
I know I'm probably missing something 
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