When Goku is defeated by the opponent and lies on the ground, he gives Krillin the remaining energy he has for the Spirit Bomb. Once Krillin forms the Spirit Bomb in his hand, he launches the attack at the opponent. When the opponent dodges the Spirit Bomb, Gohan appears and deflects the attack up into the air at the opponent, inflicting a huge amount of damage.
Goku, Krillin, and Gohan uses the Fusion Spirit Bomb during the battle against Vegeta. While Gohan fights against Vegeta, Goku (lying on the floor severely injured by Vegeta's earlier rampage as a Great Ape) gives the last remaining energy of the Spirit Bomb to Krillin. When Vegeta backs Gohan into a corner and Yajirobe yells for Krillin to throw the Fusion Spirit Bomb, Vegeta hears Yajirobe and dodges the attack. However, telepathically contacted by Goku, Gohan deflects the Fusion Spirit Bomb up at the surprised Vegeta, blasting him up into the air. Vegeta manages to survive the attack heavily injured, and continues the battle.
Appearance in Video Games
"Fusion Spirit Bomb" was named in the Raging Blast games, where it is a Team Super Attack used by Goku, Krillin and Gohan. The three need to be on the same team, and Goku must be defeated for the move to be triggered. The move can also be triggered with only Goku and Krillin on the same team. In those video games, the Fusion Spirit Bomb can defeat an opponent no matter how much health they have, the only challenge is getting the move to hit. Prior to the Raging Blast games, in Dragon Ball Z: Budokai Tenkaichi 3, the technique was simply called Spirit Bomb and it is used by Goku (Early) alone, as his Ultimate Blast.