Earth Release: Sandwich Technique

The user creates two enormous rock formations that close in on the opponent from opposing sides with tremendous force, smashing everything caught in between. Both of these formations are capable of dwarfing even the Demonic Statue of the Outer Path in size, and each half has the symbol of Iwagakure inscribed upon it. Kitsuchi stated that this was his strongest technique, standing as a testament to both this ability's destructive potential and its difficulty.

The anime shows that the technique can be used on a smaller scale against a group of few enemies.

Variation
In Boruto: Naruto the Movie, Momoshiki even able create a colossal version of this technique by simply using a single clap hand. His version lack the symbol of Iwagakure inscribed upon it and amorphous.

Trivia

 * The word sando is a Japanese abbreviation for the English word sandwich. The technique is written with the kanji for "mountain" and "earth", both pronounced with their onyomi, while they would usually be pronounced with their kunyomi as "yamatsuchi".
 * In the anime, the rock formations initially didn't have any details like the Iwagakure symbol etched onto it. They were added in a later episode.