The Doomsday Machine is a very powerful and virtually unstoppable automated massive alienrobot machine capable of destroying entire planets using powerful pure anti-proton beams. The machine then uses the planetary debris and other remains as its main source of fuel, making it a self-sustaining robot weapon.
It resembles a giant mechanical worm floating in space. Its main superstructure is made of pure neutronium, making it resilient to most forms of energy weaponry.
