Summoning: Earth Release: Tracking Fang Technique

When, for whatever reason, the user cannot find a target, they use this technique to summon a pack of ninken underground. The ninken use their superior sense of smell to track the target, converge on their location, and then all together burst from the ground and take hold with their fangs. With the target captured in this way, the summoner can easily locate them and finish them off.

During Kakashi Hatake's fight with Zabuza Momochi, he allows Zabuza to injure him a few times so that Zabuza's weapons will be coated with his blood. He then smears some of his blood on a scroll, holds the scroll in his hands as he performs the hand seals, and presses the scroll to the ground as he summons the ninken. Rather than track down Zabuza's scent, the ninken track the scent of Kakashi's blood to Zabuza. When Haku later damages the scroll, the summoning is ended prematurely and the ninken disappear, thus releasing Zabuza.

Trivia

 * In the English translation of the anime, Kakashi threatens to have the ninken kill Zabuza. Such a threat is not present in the original Japanese.