Void

The Void is the lowest layer of reality, an endless expanse of nothingness. Every black hole in the entire multiverse has a white whole counter-part in the Void. Anything that gets sucked into said black hole will be ejected from its respective white whole in the Void. That makes the void a sort of cosmic dumping ground, with debris from ruined planets and stars scattered around white holes. White holes have negative gravity, so they push everything near them away from them, getting stronger as you get closer.

In -997860 SATAN was played by a couple groups of Delarosians on Orates, causing the SATAN Wave to go out in all directions infinitely at the speed of light, the core of Orates being the epicenter. Anything that the wave touched was transported into the Void to its respective location, albeit with certain ''defects. ''The SATAN wave is still expanding and always will be, until the entire universe is sent to the void, slowly. And even then it will continue to extend until the entire multiverse is voided. However, its speed will stay the same. Heat death would've already occurred by the time it reached the boundaries of the universe. But even in a dead universe where all the stars have burnt out, the SATAN Wave will move on, taking whats left of the multiverse long after its dead into the Void.

The Void seems to be a strange medium, thats breathable and not cold. But its not air. Fires still burn in it however.