Enemies in Final Fantasy XIII are similar to those in Final Fantasy XII but unlike those in earlier games in the series. There are no random encounters as you wander through various areas of the map; instead, you can see enemies on the battlefield and dodge around them if you would rather avoid the fight.
In addition to being able to dodge enemies, you can also sneak up on enemies while they are looking away in order to initiate a 
preemptive strike. This can be triggered by having your party leader touch an enemy on the battlefield before they are made aware of your presence. You will know when they are aware of your presence because a red exclamation mark icon () will appear above their heads.
Initiating a preemptive strike will cause your party leader to run around the battlefield at the beginning of the fight hitting each of the enemies you are facing and immediately filling each of their Chain Gauges to 100%. In this state, one more hit from any attack will likely throw them into a Stagger state, allowing you to get a quick Stagger in and defeat enemies much quicker. Note that the Stagger timer will be much shorter than it normally is.
Your party members will also begin the battle with a completely full ATB gauge and this, in combination with the Stagger, will allow you to defeat enemies much quicker. This is often a way to ensure a much higher Star Battle Ranking, although it’s worth noting that many enemies cannot be hit with a preemptive strike. This is typically denoted within the relevant sections of this strategy guide.
