The Final Egg Blaster is a weapon built by Dr. Eggman during the course of Sonic Battle.
After building it, he attached it to his Death Egg and waited for Emerl to appear. After being defeated by the Gizoid, Eggman fired the Final Egg Blaster on a group of stars, destroying them. This activated Emerl's original program, which forced him to break its Link to its former Master and establish a new link with the owner of that overwhelming power. Unfortunately, Eggman's plan worked too well, as Emerl aimed the Final Egg Blaster at earth and set it to fire after sixty seconds.
Eggman, not wanting Emerl to destroy the planet (because Eggman would not have a world to rule if he did), tried to command him to stop, but Emerl knocked him out. Sonic battled Emerl before the Final Egg Blaster fired, restoring him to his old self again, but causing such damage that Emerl was destroyed as well. The Blaster was deactivated and the Earth was saved.