The mech grabs two nearby galaxies in the Anti-Spiral space, crushes them together, and compresses their matter and energy into a ball. It then unleashes the resulting pressure, combined with the Anti-Spiral's own energy, as an enormous blast of raw energy. As the name implies, it is a wave attack that consists of an endless series of Big Bang explosions. As the Tengen Toppa Gurren Lagann is shielded from this by Lazengann, new galaxies can be seen being born as a result of this energy being unleashed.
The Big Bang has the power to create and destroy entire universes. The name Infinity Big Bang Storm implies that it is a wave attack consisting of an endless series of Big Bang explosions, each one capable of creating and destroying entire universes, essentially making it a multiversal-level attack.