After focusing senjutsu chakra to it, Shima's tongue grows to its maximum limit and is reshaped with a face. The tongue will then seek out the scent of its target. When the target is found, she ensnares it to prevent escape and marks it with a corrosive chemical. After the enemy is found Fukasaku can use the Fighting Tongue Slash on it.
"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", which reflects the arguments Fukasaku and Shima have all the time. The full kanji can be translated as "War of Words Bind".