Killing Manifestation - Shoujouwo Korosu
Basically, the killing intent is controlled and concentrated to the point it actually becomes visible. Shape doesn't matter as it can be changed into whatever the user wants it to. Once the manifestation of the killing intent comes in contact with the victim, it begins to steal the life force of the victim.
Alternative to this would be if the technique was considered a powerful genjutsu capable of causing death by tricking the mind to believe they are dead. The victim would believe they're dead because of the hallucinogenic capabilities of killing intent which is shown in canon when Orochimaru makes Sasuke and Sakura visualize their deaths in training ground 44.
Pros
Can kill targets with a weaker will than the user
Takes no chakra to use
Can be focused on a certain point
Takes a short amount of time to take effect (a few seconds)
Cons
Can be tracked down through use of this technique
If not controlled properly, can effect unwanted targets
This is a technique created by me based on Killing Intent
Feel free to use it in any stories
Please review if you have any improvements or advice