The Cerberus Heavy Tank Destroyer was used by the Space Marine Legions near the end of the Great Crusade in the late 30th Millennium as a testbed for the experimental Neutron Laser Projector weapon. The Neutron Laser Projector itself was retro-engineered by the Mechanicum after being rediscovered within Dark Age of Technology battlefield wreckage recovered at great cost from the Forbidden World of Deep Hyades VI by Mechicum Explorators from the Forge World of Galatea. The Mechanicum placed the retro-engineered prototype weapon into the modified chassis of the Spartan Assault Tank, using that vehicle's large interior space to mount the sizable Atomantic-Arc Reactors and radiation shielding needed for its operation. The result of the Mechanicum's labours was a relatively small and mobile wea