The Command Nexus ship is the Drone factions version of a carrier vessel. It is capable of launching multiple waves of drone ships. It was firdt introduced as part of The Awakening event but it was then later released as a regularly activated Dynamic Mission, known as Drone Incursion.
"While a few of us do play Sins of a Solar Empire quite a bit, we just wanted to do a different ship style. All the ships are built along the horizontal access. So we wanted to experiment with the drones and making their design more vertical.
Honestly the idea for the vertical style inspiration came from the B-Wing." - Javery_BP