History

A solid barrier surrounds the Multiverse, beyond which lies the Source. It was created by the Cosmic Raptor to imprison the rogue Super Celestial, Perpetua, and her army of Apex Predators and her power since the dawn of creation. 

On the wall are the frozen statues of dead gods, cosmic beings, and foolish entities—the Promethean Giants—they tried to breach the wall and failed, only to become a part of the giant wall. The remote Promethean Galaxy is the closest point to the Source Wall. But during the Metal sagas and the breaking of the Force Barrier, it was severely weakened.

Trivia

The Source Wall, in the early tales by Jack Kirby and Gerry Conway, was a metaphysical barrier with the Promethean Giants strewn throughout.

Chris Claremont and Walt Simonson, with Marvel and DC Present #1, portrayed it as a physical wall with Promethean Giants embedded on it. Albeit this was outside the mainstream, it adhered to the appearance in future stories.

It is defined as the interdimensional purgatory at the very edge of the universe.

Doctor Doom is shown captured in the Source Wall in JLA/Avengers #3.

During the invasion of the Dark Multiverse, in order to defeat Barbatos and restore Prime Earth to its original position, the Justice League forcefully used Element X. But this caused the Source Wall to shatter and unleash the Totality.

Superman, Batman, Wonder Woman, Metron, Darkseid, Swamp Thing, Kyle Rayner, and Lex Luthor have interacted with the Source Wall and have returned.

Black Hand interacted with the Source Wall and resurrected the beings trapped within it temporarily.

Images:

Links and References

https://dc.fandom.com/wiki/Source_Wall

Ref: Swamp Thing, Final Crisis

^{Pic Credits: DC Comics}