These [battleship] ships are superseded by the even larger pre-Age of Strife advanced superships that are reserved for larger combat or exterminatus missions. Such ships are similar to the huge space forts, planetary sized battle-hulks, and doomsday bastions yet are far more mobile and capable of fighting like standard battlefleets. They are mustered in far greater numbers and utilize battleship sized escorts as part of far more powerful Devastation Blockades and Sentinal Forces, which routinely crush Hive fleets or Chaos daemonworlds, or guard dangerous powers on quarantined worlds. The most powerful ships are kept totally in secret shipyard-crypts such as the Caelan Class Sunderer vessel (rumored to be able to fire and anhilatate any target in any time or location, far too powerful to used except by the Emperor Himself) and other powerful doomsday-class voidships.