History
The Big Bang Cannons were a set of singularity disruptors constructed by Doctor Doom in anticipation to Galactus' arrival on Latveria. When Galactus made landfall, Doom deployed them to disrupt the World Devourer's subatomic structure. This caused the weakened Galactus to fall through the ground and become entrapped in Mount Doom after Victorious felled him.[1]
Since Galactus' captivity was going to cause increasingly more powerful power surges that threatened to eventually destroy the world, the Fantastic Four hijacked the Big Bang Cannons after escaping from their own imprisonment at Doom's hands. Mister Fantastic repurposed the Big Bang Cannons to resequence Galactus' subatomic structure, freeing him from Mount Doom.[2]