Battles in Final Fantasy XII are menu-automated driven. Combat is almost realy time with a system incorportated known as the active dimension battle (ADB). The gamer can take control of any of the three characters that are used in the battle party or can have them all automated to perform specific task in a particular order. The only drawback is there are scenes where the computer will have guest characters that control themseleves on their own (meaing you cannot control them). The main advantage to this is that any items they use do not widthdraw from your party.

The main commands are:

• Attack
• Magicks & Technicks
• Mist
• Gambits
• Items

These are the main abilities that allow a player to destroy an enemy or heal an ally at anytime. The drawback to this type of menu is that some of the menus can be confusing when playing on the go due to real time.

"Random encounters" have been eliminated in Final Fantasy XII; the transition to a separate battle screen like in other Final Fantasy titles is absent. Instead, enemies are visible on-screen before an engagement and the player may choose to fight or avoid them. A battle begins when the party comes within range of an aggressive enemy (or vice versa), if the party attacks a nonaggressive enemy, or if a story event initiates a confrontation. When a character or enemy begins to perform an action, target lines connect characters to other party members or enemies; different colors represent the type of action. The player may switch any active character with an inactive character at any time, unless the active character is targeted by an attack or ability. Characters who are knocked out may also be substituted. The absence of a transition to a battle screen meant the usual victory scene is also eliminated, though a successful "Boss" battle does present the player with a "Congratulations" screen and the participating characters in their victory poses. The gambit screen can change how a character will act in certain scenarios.

Another new feature in Final Fantasy XII is the "gambit" system, which allows the player to program each character to perform certain commands in battle in response to specified conditions.[20] Using gambits, the player may set reactions to different stimuli for each character. Each gambit consists of three parts: a target, an action, and a priority. The target specifies which ally or foe to act on and the condition for applying the action. For example, the target "Ally: HP < 70%" causes the character to target any ally whose HP has fallen below 70%. The action is the command to be performed on the target. The priority determines which gambit to perform when multiple gambits are triggered. This rudimentary AI programming scheme allows the characters to act on their own, although player-inputted commands are always given top priority.

Mateus, an Esper who aids in battleIn Final Fantasy XII, a mysterious phenomenon, "Mist", is the key energy which fuels two special abilities: summoning magic and "Quickenings". Summoning magic appears with creatures known as Espers, who can be acquired by defeating them in battle. Similar to Final Fantasy X, the summoned creatures become active participants in battle, as opposed to the cinematic attacks seen in early installments in the series. Unlike Final Fantasy X, however, Espers follow hidden gambits, rather than the player's direct command.The summoner remains an active member in the fight, able to attack and cast support magic, instead of leaving the party or standing idle while the summoned creature fights. An Esper will leave the battle if either the summoner or itself is knocked out, its time limit expires, or it unleashes its special attack. Some Espers have origins in the two installments of the Final Fantasy Tactics series and others are derived from the final bosses of previous Final Fantasy games, such as Chaos and Zeromus. Final Fantasy XII introduces a new Limit Break system similar to those in previous games in the series:

"Quickenings" ("Mist Knacks" in the Japanese version of the game). Characters learn Quickenings by progressing to specific panels on the License Board. Each character can learn three Quickenings, which are unique to that character. Characters may string together Quickenings into large combo attacks, called Mist Chains. If a Mist Chain reaches a certain number of attacks, a final strike will be initiated at the end of the Quickening cycle, called a Concurrence. [Tagged For Rewrite]