Soul Combination Technique

Soul Combination Technique is an S-Ranked Kinjutsu developed by the Sage of the Six Paths himself. The only known time this jutsu has been used was when the Ronin of the Hidden Destiny used it on the Yang-chakra of Kugaya.
 * Name: Soul Combination Technique (魂団結の術, Kondanketsu no Jutsu)
 * Type: S-Rank, Kinjutsu, Ninjutsu, short range, supplementary
 * Hand seals: Snake, Rat, Ram, Boar, Monkey, Snake, Ox, Tiger, Snake, Dragon, Rat, Rabbit, Ram
 * Users: Sage of the Six Paths (developer), Ronin of the Hidden Destiny

This jutsu, if successful, combines the user's and the target's souls together to form a single soul with unique properties. Thus, this jutsu really deserves it's status as a Kinjutsu, as it's practically a certain death for both the user and the target (although they don't really die in the normal sense of the word; the memories of the combined souls are passed on to the new soul created by the fusion).

To use this jutsu, the user must perform the hand seals and then touch the target's body. The touch must be firm and last several seconds, as the jutsu is not instant.