"Shikamaru's Genius" (シカマルの才, Shikamaru no Sai) is episode 86 of the Naruto: Shippūden anime.
Kakuzu manages to get the drop on Kakashi, pinning him to the ground. With no way for Kakashi to escape, Kakuzu plans to take his heart to replace the one he lost. As Kakuzu is about to take Kakashi's heart, Hidan impales himself through the heart. Shikamaru falls over, supposedly dead. Hidan mocks Shikamaru for being easily killed and prepares to walk off in order to help Kakuzu. However, Shikamaru gets up and attempts to decapitate Hidan, although his cut is not deep enough. Hidan, clutching his neck, asks how Shikamaru is still alive. In the clearing, Kakuzu is clutching his chest, wondering how Kakashi managed to strike his heart.
Both Shikamaru and Kakashi explain to the Akatsuki members in front of them that the entire plan revolved around Hidan using Kakuzu's blood for his Jashin ritual. After Kakashi had struck Kakuzu with his Lightning Blade, he had extracted his blood into a syringe and managed to pass it to Shikamaru. When Hidan attempted to cut Shikamaru's cheek, Shikamaru barely avoided the blow and squeezed Kakuzu's blood onto Hidan's Retractable Spear as well as smearing some on his cheek, in order to Hidan to think it was Shikamaru's blood. Kakuzu then falls over, supposedly dead. However, Team 10 is still faced with the crisis of dealing with the three elemental masks. Chōji attempts to use his Super Open Hand Slap to pulverise the three, but they survive. The Lightning Release mask goes inside Kakuzu's corpse, giving him its heart and reviving Kakuzu. The revived Kakuzu then has his merged Fire-Wind masks use their Strange Mask Exploding Flame technique to incinerate Kakashi, Chōji and Ino. However, the trio are saved by Team 7, with Naruto combining his new Wind Release: Rasengan with Yamato's Water Release: Tearing Torrent to create a Typhoon Water Vortex Technique that snuffs out Kakuzu's fire-wind attack.