Final Fantasy XIII features a fast-based battle system. After the player makes contact with an enemy, the scene will switch to the battle screen.
The player can only stock commands for the lead character. By consuming segments of the Active Time Battle (ATB) gauge, multi-commands can be performed at one turn, stronger commands might require more than one segment of the gauge. there is no limited MP for magic and abilities.
Attack Chain / Bonus:
Attacking an enemy charges the "Chain gauge" which increases the "Chain bonus", higher bonus means higher damage taken by the enemy, when the Chain gauge is filled, the enemy will become defenceless, this state is known as "staggered".
As for the other members of the party, the player can change their "Roles" during the battle by performing "Paradigm Shift" along with changing his own. the victory in battle is determined by the good choice of roles at the right time. there is a total of six roles:
Commando: physical and non-elemental magic attacks
Role Bonus: Slower recovery for the chain gauges of the attacked enemies.
Ravager: elemental magic attacks, building the chain bonuses quickly.
Role Bonus: Improved chain building, faster staggering.
Sentinel: enhance the defense, draw the enemy attention.
Role Bonus: Higher Physical and magical resistance.
Medic: restore HP, remove status, and revive fallen party members.
Role Bonus: More effective healing abilities and items.
Synergist: status enhancing for self and party members.
Role Bonus: Longer enhancement duration.
Saboteur: cast status ailments on the enemy.
Role Bonus: Higher success rate for the abilities.