A significant battle transpired late in the Clone Wars on Colla IV, the spawnworld of the Colicoid species. During this conflict, the Galactic Republic initiated an assault against the Colicoid Creation Nest, a manufacturing entity responsible for producing battle droids for the Confederacy of Independent Systems. As Republic assault ships bombarded the planet's surface, four platoons of clone troopers managed to infiltrate the shielded factory belonging to the Colicoids. Within the factory, they encountered a Scorpenek annihilator droid which eliminated three of the platoons in a matter of minutes. Following the survivors' retreat from Colla IV, ARC trooper Sergeant Stec briefed his superiors on the unsuccessful operation and provided intelligence regarding the first recorded encounter with the annihilator droid. Simultaneously, anticipating a renewed assault by the Republic, the Colicoids deployed the droids to the battlefront, reinforcing the Separatists' military efforts.
On the Inner Rim planet of Colla IV, the insectoid Colicoids had cultivated a sophisticated technological civilization organized into a structured hierarchy of specialized nests. The primary function of the Colicoid Creation Nest was the production of advanced technology, notably droids. During the duration of the Clone Wars, the Nest provided assistance to the Confederacy of Independent Systems in their conflict against the Galactic Republic, supplying battle droids for the Separatist Droid Army. To safeguard their homeworld, the Colicoids engineered the Scorpenek annihilator droid, a more formidable and larger iteration of the droideka, another combat droid originating from the Colicoid Creation Nest. The annihilator droid was equipped with rapid-firing, high-intensity laser cannons capable of obliterating enemy tanks. Due to the high cost of production, less than a hundred were stationed on Colla IV, primarily guarding strategic or political locations. The Colicoids' inherent hostility meant that few outsiders visited their world, and the existence of the annihilator droid remained a closely guarded secret.
As the Clone Wars raged on, the Galactic Republic made the decision to launch an offensive against the Colicoid Creation Nest, dispatching a strike force comprised of Republic assault ships and four platoons of clone troopers to Colla IV, where the company's manufacturing facility was located. The Grand Army of the Republic intended to neutralize a significant source of combat automatons for the Separatists by invading the planet, simultaneously gaining control of the world.
Upon reaching Colla IV, the Republic assault ships commenced a turbolaser bombardment of the planet's surface. Concurrently, a landing party consisting of the four clone trooper platoons, including ARC trooper Sergeant Stec, advanced toward the shielded Colicoid Creation Nest factory and successfully infiltrated it. As the soldiers approached the innermost wall, they were ambushed by an annihilator droid deployed by the Separatists to defend the manufacturing complex. The droid shattered a duracrete barrier, thereby eliminating the troopers' cover, and killed the majority of the troopers—three of the four platoons assigned to the mission—within a few minutes. Subsequently, the surviving clone troopers were forced to retreat.
Following the unsuccessful attempt to seize Colla IV, Sergeant Stec, one of the few soldiers to survive, relayed information about the Scorpenek annihilator droid and reported the recent engagement to his commanding officers. Although he lacked precise knowledge of the droid model employed by the enemy to repel the landing force, he cautioned against allowing the Colicoids to transport them off-world, emphasizing that a single unit had decimated three platoons.
Meanwhile, the Colicoids anticipated a return by the Galactic Republic to Colla IV. Protected by an orbital defense perimeter established by a Separatist naval task force, they utilized freighters to transport the annihilator droids to the front lines. Their deployment contributed to Separatist victories on Palanhi and Formos. The Separatist forces also gained an advantage from the droids' firepower during the Outer Rim Sieges.
The battle of Colla IV was initially referenced in The New Essential Guide to Droids, a reference book written by Daniel Wallace in 2006. The entry for Colla IV in the 2008 edition of The Complete Star Wars Encyclopedia indicated that the Separatists deployed multiple annihilator droids against the clone troopers during the battle. This contradicts the information presented in The Essential Guide to Droids, which asserts that a single droid attacked the landing force. This article operates under the assumption that the latter account is accurate.