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COSSACK-class Mjolnir
Production History
Designed by

Imbrium Machine Complex






Imbrium Machine Complex


241.7 kg (532.8 lbs)

  • Compressed Fullerene Buckyball Carbon Nanotubules
  • Hyperdiamond Fibers
  • UST-47B (Coyote-D7) Advanced Sensor-Scanner Cluster
  • 2U-34 Universal Uplink and Intrusion Unit
  • 7P-LCF Energy Shield Actuator Plug Components
  • X880-Boulder Emission Shroud (IMC-Spec)
  • Bravado-120-B3 Fitted Reactor Pack Stabilizer
  • P-9 Open-Line Channel Modifier
  • IR-13 Inertial Dampeners
  • 'Chronicon' Information Management A.I
  • HTI-3 Datalink
  • HDP-57 Micro Projection System
  • MU-17 External Hardpoints


"The Cossacks acted as guardians for people living on the fringes of their nation, living, fighting and surviving in the wild. Today, we pick up that mantle."
―IMC spokesperson, when revealing the COSSACK-class Mjolnir.

The COSSACK-class Mjolnir is a GEN2 Mjolnir suit derived from the RANGER-class Mjolnir. The suit shares many similarities with RANGER, including using the same basic chassis and body armor, with the main differences being in the helmet, features and capabilities of the suit.

During the designing of the RANGER-class Mjolnir, a consortium of Imbrium Machine Complex (IMC) and Lethbridge Industrial submitted two designs for the UNSC Ordnance Commission to review. The first being a simpler but remarkably tough and versatile suit for operations behind enemy lines, which was RANGER. While the other was a far more technologically advanced, but also more fragile suit, built for the same operations, this was the COSSACK-class Mjolnir.

Despite its initial rejection by the Ordnance Commission, the Experimental Armor Division of IMC would keep prototypes of the armor and work was continued in secret through the Post-War years. The suit began to enter active service in April 2558, and was operated alongside RANGER in several operations. As of October 2558, COSSACK has been in service with Spartan personnel for 5 months and has been issued to a several fireteams and individual operators.


The origins of the COSSACK-class Mjolnir precedes the introduction of the Mjolnir GEN2 and lies with the introduction of the Mjolnir Mark V in November 2551. While many designs were brought up from the Mark IV armor and many new ones were devised, there was a notable gap in the range of capabilities, more specifically the sustained long term deployment in hostile territory. With the Mark V Mjolnir, Materials Group had also begun to outsource armor design to select companies. In particular, Imbrium Machine Complex and Lethbridge Industrial were brought together into a consortium, to assist in the development of a dedicated suit of armor for independent, long term operations deep behind enemy lines.

First Rangers

" Evermann was a visionary. A fool, perhaps, and far too liberal with his designs, but a visionary. Without him, where would the Ranger armor be? Floundering in the files on one of his drives, that's where."
― Materials Group report of Dr. Evermann's involvement in the development the Ranger armor.

The lead designer supplied by Imbrium Machine Complex (IMC) was Dr. Wyatt Evermann, one of their leaders in the development of exceptionally rugged yet still capable hardware. The main focus of the joint team, under Dr. Evermann, was to develop a suit of armor which was durable enough to serve for extended periods of time behind enemy lines without support while still allowing the operator the tools to plan and execute missions with ease. Initial design proposals and prototypes of the design seemed to balance the amount of tech in the suit fairly well to the ruggedness of it. As the team progressed however, and the first prototypes began to roll out, there was a notable increase in conflict between Materials Group, Dr. Evermanns team and his Lethbridge counterpart, Dr. Bernard. The culmination of this was Evermann's sacking as lead designer and his replacement with Bernard due to his insistence of implementing advanced technologies still needed to be developed. He was therefore relegated to a consultancy role in the project where he played a still significant role which would eventually give birth to the Mjolnir Mark V/RG or Ranger.

The success of the armor over the course of the Human-Covenant War, and the expansion of contractors in the new GEN2 Mjolnir, would see IMC and Lethbridge offered the chance of bringing the Mark V/RG to the GEN2 Mjolnir platform. Though none were quite as excited by the prospect as Doctor Wyatt Evermann who had since been appointed as the head of IMC's Experimental Armor Division following the development of the Mark V/RG.

Development History

Hurdles and Division

Though before the first designs could even be drawn up, there was a rather sizeable issue. While the limitations of the late-Human-Covenant War meant the initial Ranger armor couldn't incorporate Dr. Evermann's envisioned tech suite. But this time around, he was far more insistent about not only the incorporation of his technologies but also about his role as the project head, over Dr. Bernard. The resulting conflict between IMC and Lethbridge over the development of the armor eventually ended with a near dissolution of the consortium, which was only stopped by the decision to break the joint team into two, with the IMC Team under Dr. Evermann and the Lethbridge Team under Dr. Bernard.

Conceptualization and First Models

With relatively free reign over the armor design, Dr. Evermann and his team set to completely overhauling the suit, starting with replacing the the suits information management systems and A.Is, as well as its HUD and sensors. The goal for Evermann was to allow the armor to function with near complete autonomy in the field, gathering information both passively and actively and being able to send said data back to control elements. While doable, the processing power of the suit became bogged down with the mass influx of information, which led to a rollback of the system into a simpler but still detailed three dimensional minimap for the operator. Despite this, the accompanying sensor and scanner array of the was left unchanged in the hopes of future advancements allowing the suit to take full advantage of the sensors and their information gathering abilities.

Without the limitations of wartime production, and with the advances in Mjolnir [GEN2], Dr.Evermann and his team sought to bring their vision of a completely independent operator to reality

While there had been friction between Materials Group, Dr. Bernard and Dr. Evermann, the original goal for an exceptionally rugged suit was still the main focus for the suit, even as it transitioned into a new platform. In the pursuit of this, Evermann's colleague, Dr. Aniha Chagaz, set to equipping the armor with the latest and most effective innovations in armor development ranging from hyperdiamond layered carbon nanotubes to next generation titanium-composite alloys. The techsuit, meanwhile, was of a fairly typical titanium nanocomposite blend, but was thicker and had been treated in liquid carbon fiber, primarily to allow the techsuit to sustain combat and environmental damage for long periods of time.

The final pieces of tech devised by Dr. Evermann's team was a slew of specialized accessory attachments for the armor, ranging from specially made 'flight modules' which enhance the wearers mobility during aerial insertions, to basic magnetic mounting points which could be used to carry any number of items or extra supplies. The architects of these highly modular hardpoints were Dr. Farhan Djaz, Dr. Joanna Harbin and Dr. Kim Jai.

Trial by Fire

In January 2556, both the COSSACK and RANGER-class Mjolnirs were submitted in their final forms for evaluation by spartan personnel and the UNSC Ordnance Commission. Initial tests at the Anakara Resiliency Chamber focused on simple stress testing, both armors were put through a gauntlet of intense heat and freezing cold temperatures. In addition to this, the armors were placed in test chambers which would simulate conditions such as sandstorms, volcanic smog, blizzards, hurricanes and thunderstorms. The final aspect of in-door testing was survivability tests, both armors were tested against a variety of gun calibers and even plasma weapons to test their protection, shield strengths and survivability. Both suits performed well in these tests with the COSSACK facing some issues. During the ballistic testing, it was shown that rounds which did penetrate the armor had a tendency to strike one of the many many components underneath, leading to multiple systems being compromised. RANGER meanwhile suffered far fewer penetrations and managed to retain complete functionality on successful penetrations due to its use of various back up and redundant systems. Furthermore, the large sensor array on COSSACK's helmet was prone to damage during the test, resulting in a near complete loss of anything beyond the most basic sensory information, an issue which was distinctly absent from RANGER due to its large, monolithic and heavily armored helmet.

Bosque de Negro had a reputation not just among IMC facilities but across all armor development circles for being one of the most brutal testing fields available to any company.

The second round of testing, unlike the first, would see both design teams and commission representatives maintaining active monitoring of their suits while a Spartan operator would take them through the infamously rough terrain and conditions of Bosque de Negro. Insertions into the testing grounds had an obvious advantage in favor of COSSACK thanks to its specially made attachments which offered greater agility in air and safer landings. RANGER meanwhile inserted using its inertial dampeners to insert without a vehicle, the suits more armored and rugged design allowing it to sustain much rougher landings.

What immediately followed were simulated and practical combat and objective based missions, it was here the line between COSSACK and RANGER truly came to head. The first series of missions were simple combat simulations and target fields with combat drones, both suits performed well with COSSACK noting an edge in threat management with its advanced sensors and minimap while RANGER noted an advantage in target identification and engagement times due to its unique bi-focal visor. The next set was to be a series of reconnaissance missions with combat drone patrols which is where COSSACK was assumed to show the strengths of the more capable sensors and advanced mapping system. During the testing, both armors were subject to being found and engaged by one of the patrols and would need to escape the area before others responded. COSSACK holding an advantage thanks to its mapping system and sensor array. However this was a questionable advantage as a series of minor impact to the helmet caused a tearing and distortion effect to the minimap and sensors.

The final mission to evaluate the armors would be at the centerpiece of Bosque de Negro, a large, heavily defended and monitored base known as the Kingdom. The armors were expected to break into the base and complete two sets of objectives, retrieve intel and sabotage the function of the base. As the mission got underway, there was a notable difference in the performances of the suits. COSSACK used a more methodical and slow approach to entering the base while RANGER was able to infiltrate the base with relative ease thanks to its target tracking systems keeping guards marked. Once inside, COSSACKs mapping system once again allowed much better traversal of the environment while RANGER was far more capable of responding to and neutralizing threats such as cameras, individuals and motion sensors. Once the intel had been retrieved, both were now tasked with sabotaging the base by planting an explosive charge in the base reactor The main failing point came during the sabotage procedure as the base alarms had been sounded. During the ensuing firefight COSSACK was subject to ballistic damage which this time was across the body and resulted in the failures of multiple systems across the armor.

The final reports from IMC and findings by the UNSC Ordnance Commission concluded that the technological advancement and usage showcased by COSSACK was impressive and had its own merits. However, it could not be issued in service as even minor damage caused multiple system failures, made worse by the lack of redundancies. These reasons as well as the extreme development and procurement costs associated with it compared to the RANGER-class Mjolnir. Furthermore, RANGER had proven itself to be just as capable over the course of testing. Managing to set the second highest endurance and challenge-duration records in Bosque de Negro. The conclusion was the selection of RANGER over COSSACK by the Ordnance Commission on May 22nd, 2556.

Recovery and Redesign

The failure of COSSACK, and by proxy the second failure of Dr. Evermann, left the future of the armor hanging in uncertainty. Much consideration was given to the break-up of the armor, using its various technologies to create other suits aid in the development of others. There was even talk of sacking Dr. Evermann as his grandiose approach to armor development had cost IMC tens of millions and lost them two majority shareholder positions in contracts. With pressure mounting and the Board of Directors in disagreement, a temporary solution was formulated to officially mothball both the suit and Dr.Evermann, both being transferred to the Io Design Lab. However, this was only the officially released information.

In reality, Dr. Evermann and his team had been folded under the maintenance department of the division, allowing them very limited funding and keeping their work off of official reports. Despite the stay of execution, neither Evermann or his team showed much progress, spending weeks mulling over previous test data and arguing over the allocation of their limited funds. The first actual developments came in August 2556, which was the reuse of previously developed 'flight panels' as simpler ad-hoc armor panels. These would theoretically allow a Spartan to modify and swap out plates over the course of a mission or as they were damaged. However this was rejected after cost projections for sufficiently durable plates were several times what were deemed acceptable.

However, in January 2557, there was a potential breakthrough with the design of the helmet. Back-channel connections courtesy of Dr. Djaz had unearthed a new armor prototype being tested by the Ordnance Commission. While its manufacturers were unknown, the suit itself was named FENRIR-class Mjolnir and was undergoing survivability testing which revealed a notable feature. The helmet appeared to employ an advanced battle management A.I and mounted a large scanner cluster on its forehead for optimal awareness. The particular point of interest was the sheer durability of the helmet, capable of taking repeated ballistic, plasma and blunt force impacts without fail. The exceptional performance of the helmet along with a high field of view but recessed beam visor, piqued the interest of the team who, after some legally questionable arrangements, were able to gain access to the helmet layout specifications.

"Get rid of everything, everything you wrote, everything that you used to communicate and forget the last 2 days ever happened. As far as we are concerned, this helmet was a left over development from the original project and has never seen the light of day outside of the EAD."
―Dr. Wyatt Evermann addressing his team after their last meeting with Djaz's contact.

After having finalized the overall layout and design of the helmet, the end product only marginally different from its inspiration, Dr. Evermann and his team could finally move onto the body. While visually it was very similar to its sister suit, RANGER, the boxier shape and overall thinner and less robust armor composition proved to be a particularly problematic topic. This took the form of two distinct proposals. They could wait and work out a deal with the Chairman of the Board for increased funding to rebuild the composition and design of RANGER. Conversely, they could attempt to reuse tech from other suits produced by IMC and integrate them into COSSACK. The next month was spent with little progress in talks and even less in improvements, the only meaningful changes being to the armors management software's.

However, there was a rapid shift in gears as word began to spread of the UNSC Infinity departing for a long term deployment in the next month, causing a flurry not just in the team, but in IMC as a whole. In the haste, the team decided to appropriate a number of signature masking technologies from the RECON and PATHFINDER suits, creating a 'stealth' variant of COSSACK. These prototype suits were given tentative clearance for field testing aboard the UNSC Infinity along with several other IMC armors. The would see employment during War Games where their advanced sensors and ability to hide from enemy sensors made them excellent scouting armors, but also lead to their limited use in favor of RECON.

The suits were also used to respond to pirate raids on UNSC research and trade outposts, acquiring valuable information which greatly aided in the development of their thrusters and inertial dampeners. However the main showcase of the suits capabilities was during the unexpected Battle of Requiem. COSSACK equipped forward reconnaissance teams soon found themselves conducting ambushes and raids on forces from Jul 'Mdama's Covenant and well as Prometheans. The armor, despite its rushed design, performed somewhat better than expected. While its overall protection was sub standard, the signature masking components did aid in its ability to hide, though this was ineffective against Promethean forces. The unexpected performance came from the suits sensors, the changes to the information management systems had allowed Spartans with the armor to create remarkably detailed maps and defensive positions.

Upon the return of the suits to IMC some weeks later, their onboard data having been scrubbed, they were taken apart and evaluated by Dr. Evermann and his team, along with the field test reports. Despite being heavily redacted, the performance of the suits exceeded their expectations, especially given the haste with which new technologies were adapted to it. Though the general avoidance of the suit in favor of RECON and SCOUT was to be expected. Therefore the idea of the suit as a 'stealth' suit came to an end, primarily due to the ineffectiveness of the tech relative to dedicated suits, but partly due to their new funding. As a result, both Dr. Ricard Ubezou and Dr. Erin Hawnor were brought on as armor design specialists in October 2557.

With the aid of his new hires, Dr. Evermann could finally look to resolve the most persistent issue with the suit, the protection. However the process was not to be as simple as he had hoped, as Dr. Ubezou explained the need for the composition to be fully redone, but the components inside needed to be shrunk. Cost projections had ruled out the option of a new composition built from the ground up, therefore the team was left to rework the armor of RANGER. While the legs and arms were largely identical and needed little work to modify, the chest and the advanced systems which it contained had needed significant changes. While RANGER was able to utilize a simple array of carbon nanotubes, ceramics titanium alloys and other materials thanks to its compact and less powerful systems, COSSACK was the inverse. The size and required parts for the advanced sensors and accessory systems had resulted in reducing the thickness of the armor, making it far less robust and less damage resistant.

To deal with this, Dr. Evermann and his team were tasked with working on the miniaturization and reorganization of internal systems, while Dr. Ubezou and Hawnor dealt with the armor itself. The largest changes made had to do with the armors data management and sensors systems, as the older but still very much useable hardware was simply too bulky. Itf was replaced by a new artificial intelligence working with a high speed HTI-3 datalink, allowing far more information to be processed quicker, at a fraction of the size. More importantly, this allowed for the effective flattening of the chest armor, allowing much improved ballistic protection from its sharp angled design. The armor itself meanwhile, had taken a somewhat worrying turn, even with the miniaturization of components, the thickness of the armor could not offer suitable protection without the use of advanced components.

"Sir, you've seen the performance we got from the Infinity's deployments, you've seen how far we have come, this is the last step. Please, if you can approve this funding it will pave the way for this suit to become a benchmark in operations behind enemy lines. If it doesn't, you'll have my resignation on your table before you get to the office."
―Dr. Wyatt Evermann bargaining with the Chariman of the Board of IMC for further funding.

In December 2557, after final funding approvals, the armors overall composition finally came to a close. To make up for the thinner overall armor, Dr. Ubezou and Hawnor were forced to seek alternate, high strength materials to enhance the protection levels. This culminated with the restructuring of the inner layers of the armor with coatings of dense ceramics, on a molecular level. This allowed each carbon nanotube structure to be contain multiple layers of ceramics and bolster the protection of the suit against energy weapons. However the most expensive and difficult addition was the threading of Hyperdiamond lattices into fiber like strands and threading them through the carbon nanotubes. Doing this on the inner layers of the armor dramatically enhanced protection, coming close to those of RANGER and well beyond what was needed at minimum.

With the armor composition almost finalized, there were a couple of features were insisted upon by Dr. Evermann before they finalized the suit. These being the inclusion of a wrist mounted holographic projection system to aid in mission planning, and the inclusion of inertial dampeners for aerial insertion. While the former was easy enough, the latter resulted in a delay to January 2558 for completion. By January 2558, the suit had reached its final production model, the body now looking identical to RANGER, but thanks to advancements in software and component miniaturization, it also featured its distinctive features. The suit underwent testing in Bosque de Negro and the Anakara Resiliency Chamber where it managed to set the third highest challenge-duration and endurance records. The suit formally entered service in April, 2558.

Operational History

Ambush on Demir

After repeated attacks on first civilian and later UNSC shipping in, a trio of frigates were dispatched to the Diomedes System to escort the ships through. All three ships reported repeated deployments of Space Banshees from the nearby moon of Demir, a rocky and very volcanically active moon. While piracy alone was not enough to warrant a Spartan deployment, the possibility of a Covenant cell in the region was more than enough reason to. This saw the reassignment of Fireteam Odyssey, the nearest team at the time, to investigate and report on any Covenant activity on the moon.

Fireteam Odyssey was deployed on 29th May, 2558, and began their recon soon after landing. Initial reports were largely empty, with little to no evidence of any force ever being present. However, things took a rapid turn as the team came under fire while traversing a volcano, causing them to have to look for cover in the dangerous terrain. They had been ambushed by a group of Jackal snipers situated somewhere amongst the rocks and with little indication of where. The team was forced to hold their position for seven hours, right next to an active lava flow which resulted in repeated impacts by burning hot embers on their suits. Eventually, seismic activity from the volcano managed to give a brief envelope for the team to engage the snipers area with explosives and suppressive fire. The heavy fire managed to dislodge the snipers and allowed for the team to continue their recon, finding an entire pirate base, which was reported and quickly dismantled by the team.

Analysis of the armor after the mission revealed it had managed to deal remarkably well with the incredibly hot embers from the lava flow. Showing only some surface deformation and light warping of the gel layer of the suit. The mission was also one of the first tests of high altitude insertions of the suit, which revealed the inertial dampeners to be functioning well within expected limits.

Operation: MASTIFF

In July, 2558, ONI prowlers reported a large influx of Covenant ships to the planet of Bellar II which sat in formerly Covenant held space. Further recon via drones and orbital imagery revealed as many as two thousand troops on the planet, as well as a litany of manufacturing facilities and forges being set up. They were revealed to be a new rising remnant faction called the Sons of the Journey. The alarming size of the force had necessitated an immediate response by the UNSC, fearing they could wreak havoc on resettlers spanning back into the colonies. To deal with the faction, a special order was placed and Jamie-B295, Spartan Adolphus Harvad, Spartan Elliott Richmond, Spartan Leah Kono and Spartan Kimberly Fairchild, were organized as Fireteam Nakh. These specific Spartan having been chosen for their skill and know how in long term, guerilla warfare behind enemy lines.

The deployment would prove be one of the most remarkable showcases of the COSSACK armor to date. Upon deployment Fireteam Nakh all but disappeared. Their transponder signals had been deactivated and the only indication of their continued activities were short, one sentence transmissions sent every month. Though a much more obvious indication was the growing number of devastated or vacated Covenant bases, either on fire or littered with bodies. Furthermore, there was a notable exchange of fire between two warships which left both extremely vulnerable to fire from a hijacked AAA battery. The effectiveness of the team by the end of the five month operation was very unexpected, especially their seeming ease in working together.

After returning to UNSC controlled space, having completed their mission, the COSSACK equipped Jamie-B295 and Adolphus Harvad's suits were examined. Examinations showed multiple, burns from plasma weapons on the armor as well as numerous scratches and some dents, showing the armor had faired sufficiently well over the 5 months. Furthermore, the inertial dampeners were shown to have been used repeatedly, lining up with the mission reports of the team conducting HALO jumps using captured Banshees. What was most remarkable was when the suits systems were reviewed. Copious amounts of data pertaining to their operation area, enemy bases, attack plans, detailed imagery of individuals and items of interest and even patrol routes for enemy units, were found. The Spartans had effectively created an entire battlspace map over the course of their deployment, with records showing manipulation of Covenant sensor towers.

Assassination of Tad Zhez

In 2557, there was an alarming increase in, not only the number of Kig-Yar pirate attacks but also in the size and organization. ONI contacts within the black market had revealed the existence of a new and expanding Pirate Queen, known as Tad Zhez. While her operation was still small compared to the litany of Covenant remnant factions, her use of the forces at her disposal was remarkably efficient. By July 2558, Zhez had even begun to raid research stations and colonies, leading to both an increase in the size of her forces and a large influx of weaponry into the black market. As a result of this, Jamie-B295 and her team, Fireteam Storm were deployed to the heart of her operation, the colony of Gibbana.

Initial missions focused on sabotaging or otherwise destroying numerous distribution centers and pirate camps across the colony. In one notable mission, Fireteam Storm was deployed via HALO jump to a major pirate camp, deep behind enemy lines. Over the course of four hours, the camp was systematically and methodically taken apart by Fireteam Storm, Jamie coordinating their attacks by creating a local battlemap for the team. During the deployment, B295 utilized her suits intrusion system to break into the camps comm node, allowing her to gleam valuable intel on Zhez's location.

The main operation took place in September, 2558, with Jamie-B295 and her team being deployed to the area to track and intercept Zhez as she met with an Insurrectionist leader. The team had dispersed around the meeting area, covering several entrances and exits in an effort to ensure neither target would escape. The two targets eventually arrived, accompanied by larger forces than had been anticipated, forcing several units of the team to fall back. Despite this, B295 held her position until the opportunity arose for a shot, dispatching the Insurrectionist leader and only managing to injure Zhez who had responded with alarming speed and fired back. The armor had managed to stop a burst from Zhez's beam rifle, barely managing to save B295 who was able to escape the area before any of their sensors picked her up.

Despite the missions technical failure, it had still proved immensely beneficial as one of B295's team members had managed to tag Zhez's ship. This allowed for a second deployment only weeks later in which B295 successfully took down Zhez, recovering her rifle for ONI research. The performance of the armor across the several missions leading up to the assassination were fairly minor with some creative uses by B295, such as linking all her teams binoculars to her suit, rapidly creating a battlemap. Perhaps the most impressive performance was of the actual armor of the suit, being able to narrowly save B295s life from direct shots to the chest with a beam rifle burst. Further analysis revealed the first shot had nearly broken the shields, the second breaking them and punching slightly into the armor and the third almost punching all the way through, stopping on the techsuit.

Design Specifications

COSSACK-class Mjolnir shares many similarities with its sister suit, the RANGER-class Mjolnir. Most notably the two share externally identical body armor, with the only substantial differences being the technology underneath the armor. However, the helmet used in COSSACK is a far cry from the one used in RANGER, foregoing the larger and more blocky helmet and the difficult-to-maintain bifocal visor. The new helmet featured a bulbous forehead protrusion and more rounded design on top of the head, with a more angular design present around the jaw and eye line. Notable visual cues would be the V-shaped visor, which allows a better field of view for the operator while keeping the visor low profile to avoid battle damage.

The body armor has also seen a degree of reworking, as with Lethbridge Industrial acquiring damaged or disposed of RANGER suits, there was a security concern with IMC. In response, a new, more advanced and easier-to-maintain software architecture and BIOS was developed for COSSACK and RANGER, which bears little similarity to their previous iterations. Though there are differences due to the disparity in the systems which each suit operates, with COSSACK featuring more capable data management systems.

Role and Usage

"Be it shifting sands, freezing blizzards or the depths of swamps, the inexorable COSSACK-class Mjolnir trudges on 'till the mission is complete."
―Promotional tag for the COSSACK-class Mjolnir

When COSSACK-class Mjolnir first came into service, a wide variety of of suits already in service, such as RECON, SCOUT, and PATHFINDER, seemed to have considerable overlap with it, however this was not the case. Much like RANGER, COSSACK was geared towards being a versatile suit to undertake a variety of operations, by itself, behind enemy lines and for extended periods of time.

These oprations are the suit's primary purpose and it supplants RANGER in being a dedicated suit for them. Operations focus around the deployment of a single operator or group of operators to an occupied area or generally an behind enemy lines for long periods of time. The main aims of these operations is to conduct guerilla warfare as well as general sabotage and HVT interception missions, organizing rebellion and discontent behind enemy lines and gathering information on enemy forces. These are accompanied by lesser aims such as intelligence gathering and counter-insurgency/piracy operations during peacetime.

The suits performance in these roles is facilitated by the variety of technology and components it is equipped with. Due to the use of inertial dampeners, the suit can be inserted into a combat area without the use of a vehicle, leaving no evidence to be found and making no noise. The signature of the suit is further minimized by the use of an emissions baffling system, making it much more difficult to track over distance. As the operator(s) will be cut off from outside support for extended periods of time, the suit is able to link with and break into a variety of systems to gather intelligence about its surroundings.

The suit can also allow the operator to send information back to command elements via friendly satellites such as STARS. However, is uncommon outside of specific intel gathering missions, as doing so risks compromising the operators location and impeding further operations. It also allows the suit to undertake reconnaissance missions, however this is uncommon and is usually left to dedicated suits which are better equipped for the task such as the RECON and SCOUT-class Mjolnirs.

In practice, the suit has managed to find its own niche within the multitude of Mjolnir variants and distinguishes itself as a leader in its field. Unlike RANGER, which is better suited for pointed elimination and infiltration missions, COSSACK is rather different as it focuses on creating a mapped and organized battlespace behind enemy lines. As a result of this, the system allows the operator(s) to carefully organize, plan and undertake missions with no outside help. Furthermore, it allows for the precise organization of rebel forces on a scale which few others in its class can manage, effectively acting as a mobile headquarters. As a result, COSSACK has seen a rise in popularity as a suit used by team leaders and for those operating in support of forces on occupied or contested planets. There has also been a particular rise in combined teams of RANGER and COSSACK equipped Spartans disappearing behind enemy lines and returning having dismantled whole staging grounds and bases. Mission reports from these have shown COSSACK as being remarkably efficient in planning and organizing the operations as well as undertaking them.

Armor Components


The techsuit is largely the same as the standard GEN2 Mjolnir Techsuit, composed of a Titanium Nanocomposite Bodysuit with an Inner Skinsuit. However, the version used in COSSACK-class Mjolnir is somewhat different, as it has thicker and more resistant section at all major joints such as the elbows and knees, as well as around the abdomen, chest and around the collar. The bodysuit in these areas is far more strain-resistant, due to the use of a liquid, high temperature carbon fiber wash which is woven into the surface layer of the techsuit on a molecular level. The process is typically done in a controlled vacuum chamber to allow for the safe and successful weaving of carbon fiber molecules into the techsuit. As the wash cools, it is manipulated to ensure the creation of a network of carbon fiber strands and reinforcement of the titanium nanocomposite with carbon fiber, making the techsuit far more strain resistant than its peers.

Armor Composition

Like most other Mjolnir GEN2 suits, the COSSACK-class Mjolnir features a Titanium Composite Shell which makes up the bulk of the armor on the suit. However, during the development of COSSACK and RANGER, several new forms of armor were developed. Namely, the COSSACK-class Mjolnir features two layers of new, lightweight and high strength materials, which are known in only one place outside of IMCs Experimental Armor Division.

A model of C60 Fullerene displaying the surface level hexagon structure

One of the primary layers of the armor, like RANGER, is composed of carbon nanotubes. But unlike ranger, COSSACK uses C60 Fullerene molecules, which are then compressed into a double layered structure from one of the surface hexagon structures. These are then bound together into a much larger and flatter structure. These are then used to form the carbon nanotubes, and effectively have twice the layering. The result is an incredibly strong and light layer, which has shown remarkable ballistic protection, but also worryingly high heat and electrical conductivity. While in most cases this would require a redesign due to the nature of plasma weapons, Dr. Evermanns team decided to work around the issue. To rectify the issue a lining was developed which would essentially coat the inner and outer faces of the carbon nanotubes in a layer of thin, albeit dense, ceramics. The lining would insulate each layer of the armor against plasma impacting the armor.

The inner layers are much the same as the outer layers, however they feature one key difference. Hyperdiamond Fibers are laced through the Carbon Nanotubes which further bolsters the damage resistance qualities of the layer but also allows for more layers of ceramic to be inserted into the nanotubes. Similarly each layer is combined with a thin layer of ceramic insulation to decrease the chance of any electrical current or heat damaging the suit's internal systems. While greatly increasing the cost of the armor, it allows the suit to feature ballistic and energy weapon protection close to RANGER at fifty percent of the thickness.

SPU-457 Dispersal Field Generator

The SPU-457 Dispersal Field Generator is the main shield generator of the COSSACK-class Mjolnir. It was developed from the same shield generator which was utilized by the RANGER-class Mjolnir and as a result it features a similar set of capabilities. Namely it has an above average radiation shield strength which allows the suit to operate for prolonged periods of time in extreme heat or cold and in certain high radioactivity zones. However the latter is avoided as the suit is not equipped with sufficient filtering mechanisms to spend prolonged time in these areas. Being derived from the shield generators RANGER it features compatibility with the 7P-LCF Energy Shield Actuator Plug Components which are also carried over from the RANGER. These allow the operator to adjust the overall strength of the suits energy shields to suit the needs of the mission or if they need to conserve power.

RFX-136 Compact Fusion Reactor

"COSSACK-class Mjolnir has regularly shown its capability to operate without support or detection for months on end and in the harshest conditions."
―Armory Description for COSSACK-class Mjolnir Armor.

The RFX-136 Compact Fusion Reactor is the powerplant of the COSSACK and was newly developed by IMC specifically for it, featuring a number of improvements to achieve optimal performance in the field. One such feature is the P-9 Open-Line Channel Modifier built into the reactor pack and allows for far greater control over the output of the reactor, so it can be adjusted in the field and without specialized equipment to conserve power. Similarly there is the Regal-160-B3, which is a fitted reactor pack stabilizer. The main function of the Regal-160-B3 is it allowing the reactor pack to suffer a greater amount of damage before destabilizing while being fairly low profile. Another advantage it allowing the reactor to be more efficient, this being a result of the more stable casing.

To further enhance the stealth of the suit and prevent the operator from being tracked, the reactor is equipped with a Z780-Berg Emission Shroud. While identical in functionality to the Boulder line of emissions shrouds used in other suits, the design methodology differs greatly. While the Boulder shrouds place a focus on optimal emissions masking, as they should, the Berg line focus on being compact, efficient and extremely durable. The trade off for the decreased masking is the capability of the shroud to function without issues at remarkably high and low temperatures, as well as on ocean floors and in space.


UST-47B (Coyote-D7) Advanced Sensor-Scanner Cluster

"COSSACK-class Mjolnir allows the Spartan using it to operate, map and clear out the combat zone at their discretion."
―Armory Description for COSSACK-class Mjolnir Helmet.

HM 1.png

Mounted on the forehead of the helmet in a large, bulbous, armored protrusion is the UST-47B, otherwise known as the Coyote-D7, Advanced Sensor-Scanner Cluster. Being the centerpiece of the armor, the Coyote-D7 was meticulously engineered to be a performance and quality benchmark for all other suits in COSSACKs field. The result of this engineering was a sensor-scanner cluster which would come to prove itself as invaluable to teams and individual operators.

The cluster work can work in both passive and active modes which allows for different levels of information intake at a given time. In passive mode, the scanners take high definition, broad spectrum scans of the area around the operator, out to a range of 100 meters in any direction. The information is then processed alongside target information obtained from the sensors to create a highly detailed 3D Holo-Map in place of the standard mini-map by use of an advanced 3D cartography software. The result is detailed terrain orientaton, such as elevation changes, obstacles and can even mark the orientation of targets.

In active mode the cluster can, when used in concert with the 2U-34, link to other systems to enhance its level of detail and range. It is capable of connecting to a variety of systems, such as satellites, security cameras or sensors systems to enhance the range and detail of the information gleamed by the suit. Furthermore, it can be used to take extremely accurate and detailed scans of areas either as a means of gathering intelligence, marking a target or as part of a wider plan for an operation.

2U-34 Universal Uplink and Intrusion Unit

The 2U-34 Universal Uplink and Intrusion Unit is an, encrypted, high sensitivity, broad spectrum, low-probability-of-intercept uplink unit. It is used to remotely connect to any standard UNSC terminal or device, such as data-pads, satellites, terminals and data centers over extreme distances. The advantage of such a system is its lack of reliance on any intermediary devices, such as a signal booster or direct connection which allows the operator to remain on the move. The signal can further route its connection through an included scrambler, scattering the source of any transmissions. It also has the added function of being able to remotely hack into such systems, both human and Covenant. The intrusion system works on its own channel so as to prevent the suits main systems being compromised in the event of a cyberattack.

The information obtained by the suits sensors and scanners, such as the terrain and target info, can also be routed through the 2U-34 and beamed to any nearby friendly device. In particular, the suit is rated to connect via secure and encrypted channels to STARS satellites to export or import any information. However, if the suit is unable to do so, it can offload the data during mission debriefings. With the aid of a dedicated 'Smart' or 'Dumb' A.I, the capabilities of the the unit can be furthered to allow for breaking into encrypted hostile battlenets or other secure systems. Similarly it would also allow data to be received and sent far faster due to the added processing power of an A.I.

IR-13 Inertial Dampeners

The IR-13 Inertial Dampeners allow the operator to conduct High Altitude High Opening (HAHO) and High Altitude Low Opening (HALO) jumps in absence of any vehicles or equipment. A major advantage of these direct insertions of the operator is the greatly increased stealth. By not needing a vehicle, the Spartan presents a much smaller radar, noise and visual signature, making insertions far stealthier. Furthermore, this avoids the risk of needing to dispose of or hide insertion tools such as SOEIVs and Parafoils, decreasing the chance of an enemy force learning of an insertion. Together, these allow for a significantly safer way of deploying both the suit and Spartan behind enemy lines

'Chronicon' Information Management A.I

The 'Chronicon' Information Management A.I is a purpose built suit A.I made specifically for the COSSACK-class Mjolnir. The A.I is designed to handle the large amounts of data the suit receives through the sensors cluster and other interfaced devices through the uplink module. Being a suit A.I, the Chronicon is fully capable of working in concert an on-board 'Dumb' or 'Smart' A.I. This has shown to be incredibly effective with test modules being able to run both the UST-47B and 2U-34 at maximum performance with seemingly no issues. Despite this, the process of doing both simultaneously is still discouraged to avoid risking damage or overloading of the suits processing systems. IMC's systems management A.I 'Louis', had reported a friendly behavior of the A.I but also reported instances of the A.I cataloging segments of its interactions with Louis, these were subsequently wiped.

HTI-3 Datalink

The HTI-3 Datalink is a high speed, high capacity datalink used in the armor to more easily manage the large amount of data acquired by the sensors and scanners. The datalink was specifically chosen to work in concert with the 'Chronicon' A.I and optimize the transfer and subsequent organization of data gleamed by the suit. It also extends to the exporting of information, with the datalink allowing for a far faster transmission speed which shortens the window in which the operator risks being detected. As a result, this allows both the UST-47B and 2U-34 to work at near maximum capacity with little to no impact on their or the suits performance. Though like the A.I, this is dissuaded both due to the unlikelihood of both being active at max capacity, at the same time and die to the potential risk of over taxing the processing systems.

HDP-57 Micro Projection System

An example of a projected map, areas with previously scanned enemies in orange.

The HDP-57 Micro Projection System is a forearm mounted holographic interface which can be used to project holograms of information on-board the suit. Projectable items include full size 3D maps, detailed battlespace maps and even 3D images of potential targets. As an added feature the map has the option of localizing to the operator and have them be standing on their position on the map. The system can also be used to project scenes or locations the operator had chosen to scan in extreme detail. While seemingly not a major piece of the suit, it is vital to its ability to allow joint planning of operations and organization of rebel groups.

MU-17 External Hardpoints

The MU-17 External Hardpoints are magnetic hardpoints mounted on both COSSACK and RANGER in various areas across the armor. Such areas are the upper forearms, sides of the calves, sides of the chest, hips, and on the small armored panel on the posterior of the armor. The purpose of these hardpoints is to allow the operator greater versatility in the equipment they can carry into the field, allowing various forms of ammo pouches, grenades or other equipment. A unique attachment which was left over from an older variation of the suit is the addition of signature breaking panels to escape enemy sensors as well as add-on armor panels.

Notable Users


Jamie-B295 is a Spartan-III commando, formerly of Beta Company, who had spent 9 years locked in a deadly gureilla war on the colony of Toison. Following her return, she made a request for transfer to the UNSC Army Ranger unit she served with. As a result of her posting, she was one of the first recipients of the COSSACK-class Mjolnir and has since consistently proven the armor being capable of taking the strains and rigors of long term, unsupported missions in enemy territory. Further exemplified by her and her units deployments against Kig-Yar Pirate factions, her assignment to Fireteam Nakh and several other operations.

Fireteam Odyssey

Fireteam Odyssey was the first full team of Spartans equipped with COSSACK-class Mjolnir. The team has been deployed on several operations against both former Covenant and Insurrectionist forces, often conducing protracted guerilla warfare and sabotage across entire systems. In particular, they were the subjects of an ambush on the moon of Demir and eliminated five major Insurrectionist leaders in the Diomedes System.

Fireteam Nakh

Fireteam Nakh was a specially composed fireteam of five Spartans, brought together with the specific task of crippling a rising Covenant Remnant faction in Operation: MASTIFF. Over the course of the deployment, the team was able to totally dismantle the facilities and large numbers of troops of the faction and rendered it effectively crippled, in what was one of COSSACKs most impressive uses.

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