Leviathan

The Imperial Leviathan is a super-heavy Mobile Command Center and Assault Transport that uses the same chassis as the massive Squat Colossus and Cyclops war-machines. This monstrous vehicle was supplied to the Imperial Guard as part of the mutual exchange of materials and technologies between the Squat homeworlds and the Imperium. The Imperium uses its Leviathans as gigantic mobile army group command centers for coordinating the vast numbers of men and vehicles found in Imperial Guard Regiments. The Squats employed the Leviathan as a massive troop carrier to transport special "Ironbreaker" Brotherhoods of Squat warriors into combat protected by its multiple Void Shields and metres-thick armoured walls. In essence the Leviathan is a giant land-based battleship on treads. The Leviathan has enough cargo room to hold over 2 full companies of Guardsmen and all their battle gear. The vehicle is armed with a wide-variety of weaponry, including 8 Battle Cannons and multiple Twin-linked Heavy Bolters, it's main weapon is a extremely powerful cannon called the "Doomsday Cannon", it is also known as a "Macro Cannon". Supposedly, the Macro Cannon is big enough to fit a Leman Russ tank inside of the barrel, and when fired is said to be clearly audible from several miles away and the recoil can be felt at similar distances.