WARNING: The following article contains spoilers for Dark Nights: Death Metal Multiverse's End #1 by James Tynion IV, Juan Gedeon, and Rus Wooton, on sale now.
With only six universes remaining after Perpetua's war against the Multiverse, the race is on to save as many people as possible. Justice Incarnate, the Multiverse's Justice League, united once more to rescue the civilians trapped on these evil Earths and then blow up the towers they were connected to. And Dark Nights: Death Metal - Multiverse's End shows how they could possibly rescue and then evacuate everyone living across multiple planets through the familiar DC vessel, the Carrier.
The Carrier was the ship formerly operated by the Authority of the WildStorm Universe, and it returns as the Justice Incarnate's escape plan here. This 50-mile-long sentient ship is capable of traveling through the Bleed, the space between alternate realities. This gives its passengers an avenue of temporary escape and by jumping between worlds, few can follow them, and the ship is also powered by a baby universe.
First introduced in Warren Ellis, Bryan Hitch, and Bill O'Neil's The Authority #1 in 1999, the ship was discovered by Jenny Sparks of the Authority and then used as their base of operations. The Carrier's usefulness to the Authority was not limited to traveling between realities. The Carrier was also capable of opening "doors" between points in space, allowing for quick response time to catastrophes that required the Authority's attention. In some scenarios, the Authority even used the Carrier to evacuate Earth.
Given all of its capabilities and the fact that it has been used to evacuate planets before, the Carrier was the perfect vehicle to get the survivors of the Dark Nights: Death Metal event to safety. Even though Justice Incarnate's usual mode of transportation is the Ultima Thule, the ship's limited size would not have suited their purposes like the Carrier would have. But more than that, it also reflects how the heroes have changed their approach to handling the situation. In the wake of Perpetua's takeover of the multiverse, Wonder Woman has decided to lead the remaining heroes in a more proactive approach to fighting back. She signaled this change in tactics when she cut the Batman Who Laughs in half with an invisible chainsaw.
Up until that point, the heroes of the DC Universe have been reacting to changes in the situation. The Justice League reacted when the Totality appeared, they reacted when the multiverse chose Doom over Justice, and now Batman was reacting to the changes Perpetua had made to reality. Wonder Woman has since decided that they won't waste any more time, the survivors needed to take the initiative and save the world by doing the unexpected.
Now the heroes of the DC Universe no longer merely react, but try to act first to prevent more loss of life. This is something that they by the Carrier's previous occupants. The Authority was far more proactive than reactive and using their former base of operations to take the fight to Perpetua is something the Authority would undoubtedly approve of. The first step for them is to save the survivors so that Perpetua would lose a massive source of power. After that, they would need to keep them out of her grasp, and the Carrier is the perfect ship for the job.