Introduced in Persona 3, the All-out Attack is a special technique that can be used when all enemies on the battlefield have been knocked down. Once all enemies are downed by either being struck by their weakness or a critical strike, the player will be given the choice to either engage in the All-out Attack or hold off. The amount of damage done to each enemy during an All-out Attack is generally much greater than what damage a single character could do normally. In order to perform an All-out Attack, there must be at least two standing characters in the player's party, including the main character.
The strategy surrounding All-out Attacks changed somewhat in Persona 4. In Persona 3, when a dizzied enemy's turn comes around, it will regain its footing, but won't be able to attack until the following turn. Thus, choosing not to perform an All-out Attack could give the player more time for other actions such as healing while the enemies are unable to strike. In Persona 4, downed party members and enemies are able to attack on the same turn they recover from dizziness, and so the advantages of turning down All-out Attack opportunities are lessened.
Persona 4 Arena
In Persona 4 Arena, the All-out Attack is adapted into the fighting game format as a simple command attack that is initiated by pressing the A and B buttons, and then once it connects, rapidly pressing B to deal more damage as a smoke cloud rise into the air. The attack can be finished by pressing either C, to send the opponent skyward, or D, to knock the opponent back.