Ratio Technique generally focuses on creating weak points in the user's single adversary. In most cases, it would divide one target with a ten-stroke line. However, Collapse expands what can be targetted and divided by Ratio Technique from a singular target to an entire area. The impact of this technique is so powerful it creates shockwaves of cursed energy that rips through its effective hit zone.
Nanami first used Collapse to bring his first jujutsu battle with Mahito to an end. He was unable to effectively injure Mahito's body with Ratio Technique, so Nanami decided he had to bring the fight to a close with one decisive blow.
After using his overtime vow to increase his cursed energy, Nanami activated Collapse and punched the wall of their underground battlefield. Streaks of cursed energy crumbled the wall to pieces, dropping all of the debris on Mahito.