Created in limited numbers in the latter days of the Great Crusade, the Leviathan pattern Siege Dreadnought was developed in secret on Terra, away from the pervasive oculars of the Mechanicum. Its massive frame incorporates hybridised technologies, some dating back into the dim past of humanity.Source: Forge World
Towering over later Imperial walker patterns, this heavily armoured dreadnought is savagely powerful. It was designed for siege warfare and primarily armed with close combat and support weaponry that can rend buildings, vehicles and flesh alike; though it is no less effective when armed with the powerful and esoteric short ranged weaponry uniquely developed for it. The Leviathan’s oversized reactor allows it to bear weapons more powerful than other classes of dreadnought, and also powers reinforced energy fields that surpass those developed for the Contemptor class.