It became a hotbed for eccentric Tech-Priests, whose views were often considered borderline heretical by their compatriots. Pariahs, ostracized Tech-Priests, outcasts and even the frequently shunned Magi Dominus in charge of terrifying Legio Cybernetica cohorts sought refuge in this new Forge World, whose first settlers claimed authority and welcomed variety. The founder of Draconis IV as a Forge World was Archmagos Kent Rolov, who proposed innovation and creativity as the way forward for the Cult Mechanicus, emphasizing that change and progress is the way forward, and the only way to uphold the first credo Knowledge is Power. Arguing that knowledge can only be power if the Tech-Priests were willing to expand their knowledge through innovation and creativity, exploration and experiments, Rolov believed that both power and knowledge will stagnate if the Mechanicus refused to advance and attempt new things. Having witnessed firsthand the power the burgeoning Tau Empire wielded with their cutting edge technology, Rolov was concerned that the Imperium would fall behind. Branded a heretic for his beliefs, he escaped the Prefecture Magistarium and fled to found a new Forge World on Draconis IV while receiving protection from the Knight world of Draconis III, forging an alliance with the de facto ruler of House Yato.
Shogun Yato Yoshinobu was a shrewd politician and cunning warrior who recognized the need of the three Knight houses to rely on the Adeptus Mechanicus. Despite having hundreds of aging Knight suits, he realized that their eventual wear and tear had rendered them all but ineffective in combating Xenos and Traitors alike, particularly when he was treated to a display of power by the Imperial fleet who found them. As such, he was quick to forge an alliance with Archmagos Rolov, yet at the same time maintain the sovereignity of his House, as well as that of his allied Knight houses. House Yato, House Uesugi and House Takeda greatly depend on Draconis IV to construct, maintain and repair their Knights, the grateful Tech-Priests enthusiastically upgrading and repairing the aged suits both for their new allies' benefit, and also in order to receive protection from hostile agents under Martian authority.
Archmagos Rolov also expanded on his fledging Forge World's repertoire by trying to imitate the success of the revered Ryza. While Ryza was more forthcoming with the production of plasma guns, they held the plasma technology of their vaunted Leman Russ Executioner tanks close to their chest, and the Tech-Priests of Draconis IV had to attempt countless experiments before they finally replicated a design similar in power to that of Ryza's. However, far from being perfect as they lacked the technological expertise of Ryza, the Executioner plasma cannon they produced was far more volatile and therefore prone to blowing up when attempting to focus superheated plasma into an intense beam. To further compound the problem, the Tech-Priests of Draconis IV favored installing plasma cannon sponsons on their Leman Russ Executioners, increasing the chances of overheating. However, to the cold, calculating Tech-Priests, the lives of the human crew were of little import, so long as the tank deliver their devastating bombardment of plasma energies to the enemies of the Omnissiah. There was one slight consolation, though. The Leman Russ Executioner tanks were much cheaper to produce and therefore could be massed more easily with fewer resources, when compared to Ryza. This thus allowed Draconis IV to ship a larger volume of Leman Russ Executioner tanks to more systems. With Ryza currently under siege by two massive Ork Waaagh! invasions, the Imperium of Man has taken to relying on Draconis IV's efficient production of cheaper Leman Russ Executioner tanks, even if they are no longer as safe and stable as the Ryza-pattern Leman Russ Executioner tanks. So you can basically account for your cheaper Leman Russ Executioners with the Gets Hot! Special Rule in the latest Astra Militarum Codex and credit them to my dear Draconis IV. Yay.
Furthermore, the manufactoriums of Draconis IV have also taken to replicate the once-extinct Leman Russ Vanquisher tanks, the technology for its cannon considered lost by Mars when the Forge World of Tigrus was overrun by Orks many millennia ago. Following on the successes of Gryphonne IV and Stygies VIII, both of whom succeeded in producing their variants of Vanquisher cannons. Gryphonne IV came up with Vanquisher cannons that could generate much greater shell velocity, but they got nomphed by Tyranids, particularly the ravenous beasts of Hive Fleet Leviathan. Ouch. On the other hand, Stygies VIII is still alive, but their version of Vanquisher cannons use gun stabilizers and recoil dampeners to guarantee an accurate first shot, though subsequent shots suffer after that. Draconis IV's Vanquisher cannons do not suffer from that, but admittedly they do not have an accurate first shot. They resemble more of Tigrus's original Vanquisher cannon after reverse-engineering those cannons salvaged from the battlefield (they attempted the same with Ryza-pattern Leman Russ Executioner, which is the only reason why they even succeeded in producing a counterfeit version at all, but the Ryza tech was still too sophisticated for them). Glad to say they had more success in that area, at least. They are more stable and do not suffer from decreased accuracy in subsequent shots, and mostly their Leman Russ Vanquisher tanks are equipped with a lascannon for a dedicated tank-hunting role.
Draconis IV also manufactures another Leman Russ variant, the Leman Russ Punisher, as well as the staggering amount of ammunition needed to feed its voracious appetite. The vast numbers of Leman Russ tanks Draconis IV constructs allows the nearby Imperial Guard regiment on Draconis III, the Draconian Armored Defense Force, to be a fully mechanized tank regiment, fielding large columns of armored lumbering behemoths into the battlefield. In addition to the tank manufactoriums, which also construct super-heavy tanks - the most popular of which is the Stormsword for urban combat, its sheered ruggedness and overwhelming firepower (and also because they don't have the technology to build Shadowswords, so they swap the volcano cannon for a Stormsword siege cannon instead), Draconis IV also has manufactoriums devoted to producing gunships such as the Vendetta gunship and Valkyrie assault carrier. These naval assets are permanently seconded to the tank companies of the Draconian Armored Defense Force for aerial support, and often transport airborne troops to the battlefield, notably the Draconian Stormtroopers - one of the very few but also very elite infantry companies that Draconian Armor possess.
In addition to handheld plasma weapons, Draconis IV also supply heavy flamers and flamers, meltaguns, hellguns and volley hellguns. The last two, also known as hotshot lasguns and hotshot volley guns, are delivered in huge quantities to the Stormtrooper regiments in Draconian Armor - also known as Kamikaze Troopers, these fearless elite soldiers grav-chute down from Vendetta gunships, or for larger squads the Valkyrie assault carriers, with near-suicidal fervor to strike at key installations and high-value targets with surgical precision. The Draconian Armor benefit greatly from being in such close proximity to a Forge World, being the first to receive all these highly specialized weapons and vast numbers of tanks before the remainder is shipped of to other systems.
Another faction that benefits is the Knight houses on Draconis III, and as stated before, they have come to rely greatly on the technical expertise of the Adeptus Mechanicus, who devote extended periods to repairing, maintaining and upgrading the Knights' armor. Yet, despite this dependency, the Knights are not subordinates but allies with the Tech-Priests of Draconis IV, mutually cooperating with the Mechanicus while swearing allegiance to the Emperor, and by extension the Imperium, by providing staunch security from those who view the Priest hierarchy and doctrines of Draconis IV as heretical. With the Forge World providing an indispensable amount of plasma weapons, rare Leman Russ tanks, gunships and Stormswords as well as being the benefactor of one of the largest Knight houses (the combined forces of Houses Yato, Uesugi and Takeda, anyway) in the Imperium, even the High Lords of Terra could ill-afford to sanction and alienate Draconis IV without suffering a huge blow to the survival of Mankind.