Gameplay
Final Fantasy XIII's battle system maintains the strategic nature of command-based battles. Much like in Final Fantasy XII, enemies are always visible. However, unlike Final Fantasy XII, battles do not take place as you walk up to the enemies, instead there is a small transition and players are transported to a new battle screen, separate from the main playing field. The Active Time Battle (ATB) system will return, but it will work differently from its predecessors. Users will be able to chain large numbers of commands together in order to achieve attack bonuses.
Multiple commands can be stacked into slots per turn and released at the same time to form a combo. The number of command slots increases as the characters level up. These commands include the fundamentals such as Attack, Fire, and Cure, as well as new ones such as Ruin and Radial Strike. The difference between XIII's battle system and the ATB gauge is that these commands can still be placed in the slots even though the bar has run out, and the actions will be executed once the required slots are filled up. The game does not make use of MP but introduces "cost points" for each command, which determine how many times the commands can be used per turn. Because magic cannot be used outside of battle, the Hit Point (HP) of the party is completely restored after each battle.
Battle Victory
When your party is triumphant, you will be greeted by a screen assessing your performance in battle. Earn high marks by skillfully dispatching your foes, and you may be rewarded with valuable spoils and other attractive bonuses.
Target Time
The time in which a skilled player could be expected to dispatch the enemies in question.
Initiative Bonus
Claim the bonus by sneaking up on enemies unexpectedly and scoring a preemptive strike.
Battle Duration
Your time. Beat the target time to maximize your score.
Points per second
For each second you outdo the target time, your score will be increased by this amount. Conversely, for each second you exceed the target time, your score will be decreased by the same amount.
Score
Your final score, calculated using the formula above, with a base score of 10000.
Rating
Based upon your score, you will be assigned a rank ranging from zero to five stars.
Roles and Paradigms
The "Role" system exists in order to control what abilities are available to characters during battle. Rather than having all abilities available to characters as they are learned, abilities are restricted to specific Roles, similar to the Job system of previous games. The roles are Commando, Ravager, Sentinel, Synergist, Saboteur and Medic. Commandos strike with physical, non-elemental attacks; Ravagers use elemental abilities; Sentinels provoke and absorb enemy attacks, and use counterattacks; Synergists use buffs like Shell and Brave, while Saboteurs use debuffs like DeShell and Bio; and Medics exclusively heal, using abilities like Cura, Raise, and Esuna.
Each character may only take on one role at a time, and each combination of three Roles for a given party is called a "Paradigm". Up to six Paradigm combinations may be stored at any single time. During battle, players may switch between them, called a "Paradigm Shift". Timing Paradigm Shifts correctly can fill the ATB gauges, making switching frequently in battle an advantage.