Fighting Tongue Slash

By kneading senjutsu chakra, Fukasaku's long tongue gains utmost solidity and sharpness. It then leaps from his mouth with tremendous speed and force, even tearing a hole in the bedrock and through metal pipes. With that ground-splitting power, the enemy is cut in half. The way that both the enemy and the ground itself are cut apart is reminiscent of the strike of a great sword.

In the anime, Fukasaku actually fires a highly pressurized stream of water from his mouth capable of even slicing through metal like Sasori's Water Stream Shooters that can cut through metal pipes.

Trivia

 * "Zessen" is written with the kanji for "tongue" and "battle". It can be translated as to "battle with tongues". In normal use, however, it means "war of words", or "verbal dispute", in reference to Fukasaku and Shima arguing all the time. The full kanji can be translated as "War of Words Decapitation".