Krillin wields the Spirit Bomb given to him by Goku This may also contribute to the fact that Goku mastered the Super Saiyan form to the point where it's almost a natural state to him. Despite not being able to form one as a Super Saiyan, Goku is apparently capable of using it in this form as he turns into a Super Saiyan when he destroys Kid Buu with the Super Spirit Bomb, albeit after already forming it and firing it. In the future, Goku manages to channel the Spirit Bomb energy directly into himself while he is in his Super Saiyan form, supercharging his power, giving him a Spirit Bomb-sized solar aura, and filling him with a straining fury. This is because the Super Saiyan transformation is inherently malicious and taints the heart and soul.
In Dragon Ball Z: Super Android 13!, Krillin says that Goku cannot gather the energy while in his Super Saiyan state. Likewise, once a Spirit Bomb has been fired, it is possible for one with a pure heart to deflect the technique, as Goku clarifies to Gohan and Krillin. Essentially, to use the Spirit Bomb, one must have a pure heart so they can manipulate and gather energy, otherwise the move can backfire and possibly hurt or kill the user. In the Other World, Goku is taught this move from King Kai. The Spirit Bomb is quite swift when used and, if the user is not careful, it can absolutely obliterate a planet. The creation of the attack promotes a calm breeze away from the bomb, which turns into a strong continuous gale and expels colorful bands or radiation of Northern Lights-esque aurora. Energy takes the visual form of sparkling, glittering wisps when adding to the mass that are usually blue and/or white in color.
Users of the Spirit Bomb gather huge amounts of energy from all chosen surrounding life forms and inanimate objects to conduct that energy into a massive sphere of astounding destructive power. Goku with enough energy to create a Spirit Bomb on King Kai's planet