Kaio-ken Kamehameha (界王拳・かめはめ波 lit. "World King's Fist Turtle Destructive Wave") is a combination of the Kaio-ken technique and the Super Kamehameha used by Goku. Goku activates the Kaio-ken technique and uses the Kamehameha, inflicting extreme damage depending on what Kaio-ken level he is using for the attack.
Visually, the Kaio-ken Kamehameha is almost identical to a standard Kamehameha. The only noticeable difference is that the energy wave is larger and much more powerful and the user is enveloped by the red Kaio-ken aura. As the Kaio-ken multiplier increases, the wave gets larger.
Main article: Vegeta Saga
After being battered around by Goku's Kaio-ken x3 attack, Vegeta ends up losing his temper. The Saiyan prince then flies up in the air and launches his Galick Gun, intent on destroying Goku along with the Earth. Out of fear of letting the blast hit the Earth, Goku uses the Kaio-Ken x3 Kamehameha to repel the Galick Gun. Seeing how both attacks are evenly matched, Goku uses the Kaio-ken x4, surging through the Galick Gun and blasting Vegeta into the sky. However, Goku's body is left exhausted and weakened from having used so much power. In Dragon Ball Xenoverse 2, this technique is named 4x Kaioken Kamehameha which allows the user to fire a super-powerful Kaioken Kamehameha and then use additional input to channel the ki from the 4x Kaioken into their Kaioken Kamehameha to increase its power much like how Goku did during his energy clash with Vegeta's Galick Gun, though using the additional blast causes the user to pant heavily after firing leaving them open which represents the strain of using the x4 Kaioken.
The World's Strongest
Main article: Dragon Ball Z: The World's Strongest
Goku uses the Kaio-ken x3 attack against Dr. Wheelo (which broke off one of Dr. Wheelo's claws) and then launches a Kaio-Ken x3 Kamehameha against the giant robotic scientist. After a brief Beam Struggle with Wheelo's Planet Geyser, Goku increases it to x4, allowing the blast to destroy Dr. Wheelo's fortress and send him into outer space.
Main article: Frieza Saga
During the fight with Frieza, Goku gets thrown underwater by the tyrant, who attempts to drown him. However, after seeing a vision of his friends and family being murdered and Earth destroyed, Goku regains courage and raises his Kaio-ken to x20, the highest Kaio-ken level. Goku then beats around Frieza and fires a gigantic Kaio-ken Kamehameha at the tyrant, who manages to block it, causing only slight damage to him. The blast was named x20 Kaiken Kamehameha in Dragon Ball Z: Budokai Tenkaichi 3 and x20 Kaioken Kamehameha in Dragon Ball Xenoverse 2. In Xenoverse 2, it starts off with a x20 Kaioken empowered rush before finishing off with a x20 Kaioken Kamehameha thus matching its depiction in the main series, though it does not tire out the user, though it does leave them vulnerable if the opponent dodges or successful guards during the rush.
Main article: Dragon Ball Z: Cooler's Revenge
Seeing as he was no match for Cooler in his final form, Goku uses the Kaio-ken Kamehameha against the tyrant. However, unlike his brother, Frieza, who was damaged by the attack, Cooler simply surges through the blast and attacks the surprised Goku.
Universe 6 Saga
Main article: Universe 6 Saga
During the Tournament of Destroyers in the anime, Goku uses the 10X God Kamehameha against Hit to finish him off, as he could not withstand the stress of Kaio-ken in sync with a new transformation, Super Saiyan Blue. Goku used the Kamehameha against Hit then flew in the blast in an attempt to punch Hit. Hit used his Growth technique to increase his Time-Skip and froze Goku and his Kamehameha blast in time enough for Hit to dodge.
Appearances in games
Goku can use Kaio-ken Kamehameha in the Gokuden series, Dragon Ball Z: Shin Budokai - Another Road, Dragon Ball Z: Budokai Tenkaichi 3, Dragon Ball Z: Burst Limit, the Raging Blast games, Dragon Ball Z For Kinect and Dragon Ball Z: Extreme Butōden. He has versions ranging from x2 to x20 (x2, x3, x4, x10, and x20 Kaio-ken Kamehameha) in the Gokuden series, he uses the Kaio-ken Kamehameha x20 in Budokai Tenkaichi 3, the Raging Blast series, and Dragon Ball Z For Kinect.
In Dragon Ball Xenoverse, the Kaio-ken Kamehameha appears in cutscenes during the game's Return of the Saiyans Saga where it is used to counter Vegeta's Galick Gun like in the original history. In the Xenoverse cutscenes, Goku uses the x3 and x4 versions during the historic Energy Clash with Vegeta's Galick Gun. Though the Kaio-ken Kamehameha does not appear as a skill, it is possible to use the Kamehameha and other Kamehameha skills (Super Kamehameha, x10 Kamehameha, Perfect Kamehameha, etc.) in conjunction with the game's 3 Kaio-ken transformation Super Skills (Kaio-ken, x3 Kaio-ken, and x20 Kaio-ken) by entering the Kaio-ken state via one of those skills and then performing a Kamehameha. As Yamcha and Krillin can use the both the Kamehameha and Kaio-ken (Krillin in his 5th skill set & Yamcha in his 2nd skill set), they to are capable of performing the standard Kaio-ken Kamehameha in the much the same way as the customizable Future Warrior and Goku can.
"Unleash a powerful Kaioken Kamehameha! It requires a lot of Ki to fire!"
— Dragon Ball Xenoverse 2 Super Skill description
In Dragon Ball Xenoverse 2, the Kaio-ken Kamehameha appears as three Skills: one Super Skill named Kaioken Kamehameha and two Ultimate Skills, named x4 Kaioken Kamehameha and x20 Kaioken Kamehameha, respectively. Goku can use the Kaioken Kamehameha and x4 Kaioken Kamehameha skills in his Turtle Hermit Gi (King Kai) 2 skillset, while he can use the x20 Kaioken Kamehameha in his Turtle Hermit Gi (Go) 1 skillset.
"A Kaioken-powered Kamehameha! Use additional input to channel extra Ki and power it up!"
— Dragon Ball Xenoverse 2 x4 Kaioken Kamehameha description
All of them are used by Goku and can be obtained by the Future Warrior. x4 Kaioken Kamehameha shoots a powerful Kamehameha, which can have a second burst by using more Ki, but leaves the user visibly tired afterwards, unable to act for a moment. The Kaioken Kamehameha and x4 Kaioken Kamehameha also appears in a cutscene during the The Saiyan Threat Saga which depicts the historic energy clash between Goku's Kaioken Kamehameha and Vegeta's Galick Gun. The cutscene is practically identical to the one in Xenoverse, but while Goku and Vegeta are clashing, the 2nd Future Warrior is shown enduring a Bomber DX from Nappa, then defeating Nappa with a Final Shine Attack-like energy wave just as Goku's x4 Kaioken Kamehameha overpowers Vegeta's Galick Gun, which forces Vegeta to turn himself and Nappa into Great Apes using a Power Ball.
"Slam an opponent with a x20 Kaioken, then unleash a super-powered Kamehameha!"
— Dragon Ball Xenoverse 2 x20 Kaioken Kamehameha description
The x20 Kaioken Kamehameha adds a x20 Kaioken empowered rush during which he user prepares a Kaioken Kamehameha by chanting while knocking the opponent away with a punch then pursuing after them to deliver another punch that knocks the opponent away while the user fires off the x20 Kaioken Kamehameha as a finisher. The x20 Kaioken Kamehameha becomes available for purchase from the Skill Shop after completing the Cell Games portion of the main story.
- In Budokai Tenkaichi 3, the x20 Kaio-ken Kamehameha is misspelled as "x20 Kaiken Kamehameha".
- In Xenoverse 2 however it is spelled "x20 Kaioken Kamehameha" as Kaio-ken is not hyphened in the Xenoverse series.