Seizetsu Kihenkei: Pharyngeal Alien Serpent

After quickly modifying his physiology, Ace's lower ribcage opens wide before releasing intestines from his body, with a specialized head and mouth on the end. Identifying the target via specialized ESP, it rapidly travels towards the target ripping through everything in its path, even tempered, chakra hardened steel, as it seeks out its prey. Due to Ace having modified his body unknowingly beforehand, the extension itself is highly resistant to damage, going as far as taking a slash from 's sword and an enhanced unharmed. It moves with such speed and agility that it can evade arrows fired from Susanoo with ease. As shown in his battle with Sasuke, the extension is capable of swallowing full-sized shinobi whole, assimilating them into Ace's body afterwards. It has enough jaw strength to amputate the arm of Sasuke's Complete Body Susanoo.

Trivia

 * This technique was inspired by the Orochimaru snake-like extension used by Kabuto during his fight with Itachi and Orochimaru
 * This technique is based on the used by certain animals, as well as the second mouth of the Aliens featured in the Alien franchise.