A Leviathan Pattern Siege Dreadnought of the ancient Space Wolves Legion was one of the ancient Dreadnought patterns of the Legiones Astartes that made use of an Atomantic Arc Reactor.
An Atomantic Arc Reactor, also called simply an Atomantic Reactor, is an arcane miniaturised plasma reactor technology based on a form of nuclear fusion originally developed during the Age of Technology that was sometimes employed by various early Dreadnought patterns of the Great Crusade and Horus Heresy. Even in that era, its workings were poorly understood by the tech-priests of the ancient Mechanicum.
An Atomantic Reactor is more powerful by far than anything of its size in current Imperial manufacture, and is a prime example of archeotech.
The Atomantic Reactor provided a great surplus of power for those Dreadnought patterns like the Contemptor Dreadnought and other Legiones Astartes vehicles that employed it, and in particular allowed them to deploy Atomantic Shielding or an Atomantic Deflector and more powerful heavy weapons.
However, if the Atomantic Arc Reactor is breached in combat, it is prone to catastrophic failure, dooming the Contemptor chassis or other vehicle it is embedded within to utter destruction. The miniature nuclear fusion explosion generated by its inevitable destruction is also prone to causing considerable damage to nearby allied units.
Sources[]
- The Horus Heresy - Book Six: Retribution (Forge World Series) by Alan Bligh, pp. 235-237, 292
- The Horus Heresy: Legiones Astartes - Age of Darkness Army List, pp. 11, 76-77