At least one member of the testbed class belonged to the navy of the Galactic Empire. That vessel was equipped with two Orbital Bombardment Particle Cannons, which were both used to bombard a brown terrestrial body from space. The Onager-class Testbed was considered to be a less well-rounded capital ship compared to the finished Onager-class Star Destroyer, which was eventually fielded by the Empire.
The Onager-class Testbed was first pictured, albeit unnamed, in "A New Age of Battle," an article published by Fantasy Flight Games for the Star Wars: Armada miniatures game on their website on August 1, 2019. The name was then provided by the article "The Siege Breaker," also published by Fantasy Flight Games for Star Wars: Armada, on November 25, 2019. The ship had been created for a card of the same name in the Onager-class Star Destroyer Expansion Pack.
The Onager-class Testbed was first pictured, albeit unnamed, in "A New Age of Battle," an article published by Fantasy Flight Games for the Star Wars: Armada miniatures game on their website on August 1, 2019. The name was then provided by the article "The Siege Breaker," also published by Fantasy Flight Games for Star Wars: Armada, on November 25, 2019. The ship had been created for a card of the same name in the Onager-class Star Destroyer Expansion Pack.