The Cydonia-class Command Prowler is a heavy classification of Prowler, a modification of the Athena-class Heavy Prowler, and is specially modified to be utilised as a command vessel. With only three in existence, they are the rarest UNSC vessel, next to one off Myth-class Dreadnought. They were built as mobile command bases, should existing positions be compromised. One was built and tailored for ONI's director and staff, one for UNSC High Command and a third as a standby, should either of those be compromised.