Stranger of Paradise: Final Fantasy features several advanced combat mechanics. Some relate to a specific class, others are universal. Soul Break is a universal combat mechanic that is essential for real progress in the campaign.
The theory of fractions
Every enemy in Stranger of Paradise, even the bosses, has a second bar under their health bar. This beam is known as the fraction gauge. Sekiro, Jedi Fallen Order, and others have also used similar mechanics in their titles. In order to initiate a Soulbreak, the rupture meter must first be empty.
The best way to break this bar is to exploit your opponent’s weakness. Each enemy has different weaknesses to certain combat abilities or special moves. Using these attacks judiciously deals heavy damage to an enemy’s Pause Gauge. Once you’ve cleared the Fracture Gauge, you can now activate the Crack Soul technique.
When an enemy is stunned due to depleting the Rupture Gauge, a Soul Rupture can be used to finish them off. Approach the stunned enemy and use B/Circle to initiate Soulbreak. Consider it a guaranteed final move. Jack will grab the enemy, fill them with red blood crystals and smash them to dust.
Successful Soul Break attacks fill the MP gauge and restore lost magical power. Careful management of enemy weaknesses, magic weak spots, and counters is essential to consistent use of Soul Break.
https://www.gamepur.com/guides/how-to-do-a-soul-break-in-stranger-of-paradise-final-fantasy-origins How to make a soulbreak in Stranger of Paradise: Final Fantasy Origins