Crisis Core: Final Fantasy VII uses a new battle system not found in any of the prior Final Fantasy games. The system is called "Digital Mind Wave (DMW)" and comes in the form of the slot machine-like set of wheels that appear in the upper-left corner of the screen during combat. The DMW consumes 10 Soldier Points (SP) each time it spins (which is done automatically) and is responsible for triggering Zack's Limit Break attacks, his leveling up, and the leveing up of his equipped materia. The DMW acts on its own accord and there is no way to start or stop it manually. The only way the DMW will not spin is if Zack has nine or fewer SP or is under a Curse.
Although the outcome can be considered random, the DMW behaves in a very predictable and orderly fashion.
There are 18 DMW Images, but only Angeal and Sephiroth are available at the start. The others are added to the DMW as you progress through the story and obtain valuable items and materia in Mission Mode. Only human characters appear in the standard DMW wheels.
Lining up three of the same DMW images during the Modulating Phase yields a Limit Break. This first rewards Zack with a Power Surge in which he gains SP and a moderate amount of HP, MP, and AP. Any actions Zack was in the middle of executing will be carried out, then he'll perform the LImit Skill associated with the DMW images that were lined up.
Each Limit Skill is rated between 1 and 5, with the higher level skills being more powerful. Attack skills target an enemy at random and pose no elemental properties, nor are they characterized as physical or magical - they penetrate all protective barriers and always hit their mark!