Technobeasts were a combination of mechanical components and organic matter, specifically Sithspawn mutants that were part machine, part organic. They came into being when living beings were infected with the nanogene spore, a technovirus that resulted from the fusion of Sith alchemy with a Force technique known as mechu-deru. This virus induced the growth of metallic growths on the host's body, ultimately lobotomizing their brains and converting them into weaponized cyborgs. The virus infected various species, leading to diverse and grotesque fusions of metal and flesh.
During the latter years of the New Sith Wars, a Dark Lord of the Sith named Belia Darzu developed a dark side ritual called mechu-deru vitae, which she used to create her personal army of technobeasts, known as the Metanecrons. Lord Darzu housed these creatures in a concealed stronghold located on the planet Tython, and deployed them against the Galactic Republic and the Jedi throughout the two-decade Sictis Wars. The assassination of Darzu subsequently halted the creation of these Sithspawn hybrids, and they fell out of use following the conclusion of the New Sith Wars.
The defining feature of technobeasts was their infection by the nanogene spore, a technovirus that could transform living tissue into metallic components. This technovirus, composed of microscopic nanogene droids, instinctively targeted the victim's brain, lobotomizing the frontal lobe and eliminating higher cognitive functions. At this stage, the transformation into a Sithspawn hybrid became irreversible. However, before the lobotomy occurred, it was possible to stop the transformation using the Force, or through the application of intense heat to eliminate the nanogene droids. Although initially considered intelligent, technobeasts subjected to prolonged exposure to the nanogene spore experienced severe mental deterioration, impairing their motor skills and reducing them to clumsy, staggering automatons.
After the transformation was complete, most of the creature's original living tissue decayed, leaving only remnants of skin and sinew surrounded by metallic fragments, rods, and wires. The transformation also damaged the victim's vocal cords, preventing them from speaking. Because of the inherently experimental nature of the nanogene spore, the transformation process varied, resulting in unique characteristics for each technobeast. Some creatures displayed zigzagging scars where the virus built upon its own metallic structures. In other instances, victims developed multiple heads or crab-like pincers.
Designed primarily to cause destruction, most humanoid technobeasts had their arms replaced with skewers or saws, while others possessed jagged blades extending from their elbows. Larger technobeast types, particularly those derived from rancors and banthas, were converted into war machines. The mutated rancors, for instance, wielded an enormous claw resembling a club, and were also known to bite their enemies. Both rancors and banthas were fitted with spiked armor plating to replace their natural hides, and blaster cannons were fused to their shoulders.
Technobeasts, being infested with the nanogene spore, could transmit the virus to other living organisms, potentially transforming them into similar creatures. The humanoid variants could release clouds of the technovirus from their mouths. During combat, these creatures became enraged and relentlessly attacked their enemies in large numbers. However, despite their aggression, technobeasts moved in a slow and cumbersome manner. They were also susceptible to powerful energy blasts from the Force, as well as Sith lightning and lightsaber strikes.
Thousands of years before the Great Sith War, a select group of Sith magicians discovered mechu-deru, a Force technique that allowed them to manipulate mechanical structures. Using this ability, the Sith created technobeasts, which were part-machine, part-organic hybrids. Due to its limited practice, the power of mechu-deru gradually faded into obscurity.
Later, during the era of the New Sith Wars, a Dark Lord of the Sith named Belia Darzu studied mechu-deru in conjunction with Sith alchemy. Drawing on her knowledge of both, Lord Darzu developed a new technique called mechu-deru vitae, which she used to transform living beings into technobeasts via a nanogene virus. These technobeasts, bound to Darzu's will and empowered by the dark side, were created and housed within a secret fortress on the planet Tython. Inside this stronghold, a variety of living beings from various humanoid and non-humanoid races were transformed into technobeasts, forming an army known as the Metanecrons. Darzu also created a holocron containing her knowledge of the techniques used to create these Sithspawn creatures.
Belia Darzu's technobeasts were deployed against the Galactic Republic and the Jedi Order, becoming a symbol of terror during the two-decade Sictis Wars. In battle, these mutated hybrids infected other living beings with the nanogene virus, assimilating Darzu's fallen enemies into her cyborg army. However, on one occasion, a Jedi Knight managed to resist the virus's full transformation, preserving his identity and becoming known as the "technobeast Jedi." By the end of the Sictis Wars in 1230 BBY, the creation of new technobeasts ceased following Darzu's assassination, which crippled her army. Despite this, subsequent Sith Lords continued to use the creatures, albeit in smaller numbers. The use of technobeasts ended with the defeat of the Sith at the Ruusan campaign in 1000 BBY.
More than two centuries after the demise of Lord Darzu, some of her technobeasts remained active within her stronghold on Tython. Years of neglect had left them dilapidated and rusted, causing their weapons to malfunction. Furthermore, the creatures suffered mental and physical deterioration due to the long-term effects of the nanogene spore. Drawn to the dark side energy emanating from the holocron of Belia Darzu, the surviving technobeasts gathered around the device within the inner sanctum of the Tython fortress.
In 990 BBY, a Sith Lord known as Darth Bane encountered the technobeasts on Tython while seeking the holocron of Belia Darzu. When Bane attempted to retrieve the device, the horde of mutated cyborgs immediately attacked him in waves. Despite their efforts to kill the Sith Lord, the creatures were unable to penetrate the defenses of his orbalisk armor. Throughout the battle, the technobeasts infected Bane with the nanogene spore, spewing clouds of the virus in his vicinity. However, the orbalisk parasites on Bane's armor were able to eliminate the virus from his body, preventing his transformation. Despite their persistent attacks, the technobeasts inside the fortress were ultimately destroyed by Bane.
Centuries later, Sith scrolls containing Belia Darzu's knowledge of mechu-deru were obtained by Roganda Ismaren, an agent of the Galactic Empire. Moreover, Roganda's son, the cyborg Irek Ismaren, possessed an accelerated mastery of mechu-deru through a brain transplant. Together, they had the potential to create and unleash a new horde of technobeasts upon the galaxy. During the Yuuzhan Vong War, the technobeasts and the methods used to create them were discussed in Droids, Technology and the Force, an essay by Jedi Knight Tam Azur-Jamin.
The technobeasts were initially mentioned without a name in Tales of the Jedi Companion, a roleplaying supplement published by West End Games in 1996. They were referenced again, still unnamed, in The Lost Art, an adventure seed featured in the 2001 article The Emperor's Pawns. In 2005, these references were retconned by Abel G. Peña, who named the creatures in a Hyperspace fan club article called Droids, Technology and the Force. The New Essential Guide to Droids provided more detailed information about the technobeasts in 2006, along with the first images of the creatures, created by artist Ian Fullwood. The technobeasts made their first formal appearance in Darth Bane: Rule of Two, the second novel in Drew Karpyshyn's Darth Bane Trilogy. The Junk Golem figurine included in The Force Unleashed miniatures set was at one time referred to as a "technobeast." In the third part of The Imperial Warlords: Despoilers of an Empire, the alchemical creations of a character called Cronal were also termed "Trailian technobeasts."