Goku charges a Super Kamehameha, but prior to releasing it, he uses Instant Transmission to get behind his opponent and fires the Super Kamehameha, inflicting a great amount of damage. Its power comes from both of how it surprises the opponent and from the Super Kamehameha's force.
Video Game Appearances
Goku uses this technique in Dragon Ball Z: Burst Limit. He has to be under attack while charging the Instant Transmission Super Kamehameha in order to automatically use Instant Transmission to appear behind the opponent, otherwise the attack will fire as a normal Super Kamehameha.