Genkou's Giant Sand Gourd

Name: Giant Sand Gourd
Rank: S-Rank
Description: Using a large summoning scroll, Genkou summons giant sand gourd that is about two stories tall. It takes nearly 95% of Genkou’s chakra to infuse all the sand inside the giant gourd with chakra. Genkou only summons this gourd whenever he is fighting powerful ninja such as the Akatsuki. He keeps the giant summoning scroll hidden inside a small summoning scroll.

This would more like be S rank.