Death Penalty Glitch
From Final Fantasy Wiki
The Death Penalty Glitch is an aspect of the game Final Fantasy VII where a player kills enough enemies with Vincent Valentine's Death Penalty, or having enough AP on Barret Wallace's Missing Score that damage overflows. When the damage overflows, the game registers it as a bug, and will instantly kill the enemy that was hit.
To perform the overflow, either kill as many enemies as possible with Vincent (This caps at 65,535 kills), or fill Barret's Missing Score with mastered Knights of the Round materia.
There are two ways the overflow may occur. The first is when the base damage of a characters attack is applied to the enemy's defense. If this damage exceeds 262,144 damage, the overflow will occur. The second danger occurs right when Random Variance is worked out which is after all the things like Berserk, Frog, Critical Hits and the like have been added. If the damage before Random Variance goes above a random value from 524,288 to 559,094, the damage will overflow.
