The Mortis Drone is the most basic "soldier-Construct" fielded by the Mortis species, although it is by no means the most common - Mortis Micro-spores are far greater in number. The Drone is itself little more than an extremely adept predator animal, its body bristling with an arsenal of physical weapons and features which no naturally-evolved creature could hope to match. Drones attack their enemies in packs, overwhelming them, and charge the Directorate lines in vast swarms to soak up gun-fire and form a living shield for larger Mortis Constructs.
Mortis Drones, at first glance, appear to be quasi-bipedal, standing primarily on two large reverse-jointed legs (similar to the 'raptor' species of dinosaurs). However, they are in fact octapedal - having eight limbs, like spiders - the "outer" pairs [first and last] are simply more prominent. They are capable of moving on as few as two of their limbs [their back legs] as well as crawling using four or eight, depending on the circumstances. A drone is, on average, about 3 meters long from the muzzle to the tip of the tail and stands somewhat shorter than an adult human male in Directorate infantry powered armor, when measuring from the creature's shoulder, although if the Drone stands up straight it is obviously much taller than a human being. Perhaps the most prominent feature of the Drone are its front limbs. The hands of these two arms have two thumbs, one per side, and two long clawed fingers. Between these two fingers extends a huge scythe-like talon, like a scimitar blade, that appears to be formed from two additional middle fingers having fuzed together: rather akin to a praying Mantis. These talons, when not in use, fold up against the hands and rest in slits through the palms, allowing the creature to make full use of its front limbs for grasping and manipulation. The middle two pairs of limbs are smaller and less muscled, ending in hands with three fingers and two thumbs. The digits of these hands have less prominent claws and spend most of their time folded up against the creature's bodies, being used primarily for climbing, crawling and more delicate manipulation of objects [when the prominent talons of their forelimbs would be an obstruction]. Drones, like most constructs, are protected externally by a tough bone-like exoskeleton of a reddish brown coloration, although they are vertibrates and have a durable internal endoskeleton as well. Additional dark grey / black chitinous armor plates cover much of the creatures' bodies, and are capable of absorbing a degree of gunfire. The coloration and toughness of these armor plates, in addition to the overall high mass-to-size ratio of the Drones, has led the Directorate to assume that they contain large amounts of heavy metals, likely tungsten.
In addition to its array of talons, a Drone's tail is tipped with a large blade-like boney protrusion, like that of an Aliens Xenomorph, that can cleave apart battle armor as well as flesh and bone. This tail spike is regularly used as a stabbing weapon, impaling Directorate soldiers through the face or thinner points of their battle armor. Furthermore, an organ in the base of the creatures' necks is capable of, by unknown means, creating naturally-generated plasma. The Mortis Drones use their powerful throat muscles to vomit a liquid-like substance which, by some unknown chemical reaction, ignites into plasma upon contact with air. The volatility of this substance is sufficiently dampened, perhaps by means of some substance in the Drone's siliva, that it does not ignite until after leaving the creature's mouth. As a final resort, the Drone may also employ its teeth as a weapon. It has four large, powerful, toothed mandibles and a lower jaw that retracts further inside its skull, with the mandibles folding up to completely cover the mouth. The segmented armor plates on the outsides of the mandibles effectively protect the vulnerable, muscle-like flesh of the jaws when the mouth is fully closed. A Mortis Drone possesses three pairs of eyes, although they are not always open at the same time. Each eye in a pair, like those of a chameleon, is capable of looking in two different directions at once, and the pairs see in different spectrums of light - meaning a Drone is as adept in night-time conditions as in day and can detect many different forms of radiation, allowing it to home in on targets by searching for electrical signatures.
The Mortis Drones are very resilient, especially against blades and blunt-force trauma. The natural armor plates that grow over parts of their bodies are as durable as most metals, and would be rather impervious to conventional 21st century smallarms fire. The Directorate's hypervelocity, self-propelled, armor-piercing explosive ammunition, however, is another matter entirely - although the drone's armor and natural toughness is enough that one shot, unless well placed, would not be enough to bring it down. A Drone's cells, similar to those of a genetically-modified Janissary infantryman, have resilient cell walls and a very rapid life-cycle, meaning that the organism, if left to its own devices, will heal through most non-lethal injuries quite quickly. Captured living Drones have been subjected to injections of all manner of diseases, viruses and parasites, and have shown to be completely immune to all of them.
One of the Drone's - and indeed, most if not all Mortis creatures' - most interesting characteristics is the large "crest" on their heads, similar to that of a Terran Triceratops dinosaur. This crest is an extension of the armor plating covering the Drone's head and also part of its skull, though it is neither hollow nor passive in function. In addition to acting as a shield against gunfire for the rest of the creature's body, obscuring its back from view, it contains an extension of the Drone's brain in the form of vast interconnected webs of nerve endings and sensory glands. Thus it performs a function similar to that of a radar, passively taking in all manner of sensory information, and may also be a receiver [and possibly transmitter] node for the Mortis's psychic communication.
A Mortis Drone, being a genetically-engineered weapon of war rather than a natural creature, has a biologly markedly different from a normal animal. They possess four lungs and breathe through gill-like slits on their necks, which are capable of functioning underwater as well as they do on land. They also appear to have a number of interconnected hearts, almost like a digestive tract, anchored along the undersides of their spines and running from behind their throat all the way back to their sternum. By far their largest organ, however, is their stomach, which seems to combine the roles of several different organs, like the liver, appendix and kidneys. A Drone's muscles are very prominent and dense, giving them incredible physical strength, and they appear to have multiple redundant nervous systems and veins. The creatures seem to exist in a perpetual state of adrenaline-fueled hyper-aggression, rarely growing tired, constantly moving and acting agitated. As such, their life cycle is most likely rather short.
A Drone is capable of sprinting at very rapid speeds and could feasibly keep pace with a Terran cheetah. In addition, it may maneuver over almost any terrain and crawl even over vertical surfaces like ceilings. They have also been shown to be adept swimmers, and their feet possess the same two opposible thumbs and three fingers as their hands, almost like a monkey, so they have no trouble scaling most surfaces quite rapidly. Finally, the powerful muscles of their rear limbs allow them to leap considerable distances, pouncing on their foes and knocking them to the ground.
Although incapable of forming speech of any kind, Mortis Drones are not stupid. In addition to their latent psychic communicative abilities, which all Mortis constructs share, they can communicate to other individual Drones through a complex code of vocalizations and exhibit highly coordinated, pack-like behavior. Captured Drones have been subjected to Pavlovian word association expiriments, and have been shown to be capable of learning the meaning of various human words and phrases, although their hyper-aggressive nature rules out any possibility of training or domesticating them.