Vagabond-class Fleet Carrier

The Vagabond is the first class of transuniversal fleet carrier. It was introduced during the Last Age of Abyss to enable the Abyssans' escape from the dying universe.
Based on the design of earlier fleet carriers but scaled up by a lot, the Vagabond caused some upheaval by combining a massive ship designed to transport thousands of small craft along with their crews and passengers numbering in the millions total, with what was essentially a prototype drive system.
Even the most desperate Abyssans were skeptical as to whether it would work as advertised, not least because the technology had been devised by the Entropists. Still, it was their only hope at that point, and none of the smaller ships could power their own anomaly drive.
As history has shown, it did work. Later versions of the class were improved from the arguably rushed original design, providing better amenities for the long travel times during the regular migration periods of the Exile Fleets.

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Drive System

The anomaly drive is a shipboard drive capable of punching through the Veil between universes, creating a temporarily stable wormhole. To keep the ship safe from the massive detonation resulting from its collapse, the wormhole stays open for some time after the ship exits, allowing it to get to a safe distance.
Jumping an entire fleet to another universe thus requires a good deal of coordination between the ships involved, lest the last to arrive are blasted by the to shreds by the collapsing wormholes created by the first. The Vagabond also minimizes that risk by reducing the total number of ships involved in the jump.
Due to the immense power demand, anomaly drives can only be mounted on ships in the megaton mass range and above, as they're the only ones able to carry kugelblitz reactors and the required fuel. The smallest ships capable of that need one low-mass kugelblitz black hole in the low hundred exawatt range to power the drive. A Vagabond needs six of them at maximum load.