- "At the dawn of time, the Monitor placed quantum towers on key Earths as a last line of defense. The red skies are dissipating, which means it's working."
"From this design it looks like the tower is capable of generating a quantum-flux field; which could, theoretically—"
"Reverse the exogenic state of the antimatter wave; thereby, dissipating the antimatter energy."
- —Harbinger, Querl Dox and Ray Palmer on the quantum towers' purpose[src]
On December 10, 2019, one buried beneath National City on Earth-38 rose to the surface, fending off the antimatter wave approaching the planet. It worked for a little while, but after an army of shadow demons attacked (as Harbinger warned would happen), the tower was struck and the skies turned red again. Supergirl and Superman began using their heat vision to solar charge the tower's panels, but it simply slowed the wave down; only delaying the destruction, though this did buy enough time to finish setting up a colossal transmatter portal to begin evacuating the planet. Ultimately, the shadow demons overwhelmed the tower, leading to the antimatter destroying Earth-38.
The remaining towers were eventually destroyed as well, despite the best efforts of Paragons J'onn J'onzz and Earth-96's Clark Kent to save those universes' residents by evacuating them to Earth-1. With the eventual destruction of Earth-1, which had no quantum tower, no Earths were left in existence.
Behind the scenes
- While quantum towers themselves don't originate from the comics, their physical appearance strongly resembles cosmic tuning forks; which were key to stopping the Anti-Monitor in the Crisis on Infinite Earths comic.