"I have no use for a paralyzed Saiyan! You're dead-weight now!"
First, Vegeta generates electricity around his chest and converts it into a bluish-white aura around his body. Then, he thrusts his chest forward and fires a huge energy wave at the opponent, inflicting a high amount of damage as well as causing the opponent's body to violently contort.
Vegeta uses this attack to kill his former comrade Nappa. After watching Nappa's defeat by Goku and marveling at the latter's abilities, Vegeta is disappointed that Nappa, an elite, lost to Goku, a low-class warrior. As Nappa is begging for Vegeta's help, Vegeta deceives Nappa into thinking that he was going to help him: he throws him high into the air and destroys him with the Galaxy Breaker, much to the shock of Goku, Gohan, and Krillin.
A little later, Goku uses his aura to fire a Kamehameha-type wave from his body to blast a gigantic rock during a storm causing a great avalanche into a cordillera in a manners similar to the Galaxy Breaker, helping Piccolo to save a school bus full of children. The Saiyan performs this attack while he and Piccolo learn to drive with Yuzukar and Cynthia.
Vegeta also used this attack against Cabba in the manga version of Dragon Ball Super in order to make him access the Super Saiyan transformation, but Cabba managed to disperse the blast upon becoming a Super Saiyan.
Video Game Appearances
Galaxy Breaker was named in Dragon Ball Z: The Legend, where it appears as one of Vegeta's special attacks. It also appeared in Dragon Ball Z: Budokai, being shown recreated in the 3D cutscene depicting Nappa's death.
In Dragon Ball FighterZ upcoming DLC, Galaxy Breaker will appear as Base Vegeta's Meteor Attack.