The explanation of how the Limit Break ability works is provided in the game, but it's worth reiterating here, as understanding its inner workings is essential to maximizing the damage you deal while using it. Here is how it works:

In-Game Title	Description
Details	Temporarily improve attributes by channeling the power of Ifrit. This is also known as semi-priming. Recommended for use after staggering an enemy or when Clive’s HP is low. Duration is determined by the number of gauges full at time of execution. Can be used at any time regardless of Clive’s recovery status. Cannot be KO’d while semi-primed, even if HP is lowered to 0.
Attributes	Changes attack style. Doubles spells. Increases Charged Magic, Magic Burst, and Precision Shot potency by 10%. Increases Eikonic Ability potency by 10%. Slowly restores HP. Increases Defense by 10%. Prevents stagger when taking damage.
Upgrade	Adds a third Limit Break Gauge.
Mastery	Adds a fourth Limit Break Gauge.
Battle Techniques	Limit Break - Execute a Limit Break. Semi-Prime Finish - Defeat an enemy while semi-prime.

Advanced Tactics

• Pressing and will activate Limit Break, but you can also press them again to deactivate it if the enemy is defeated or the stagger window is over. Note that you can’t recover a partial Limit Break gauge, though, so if you’re halfway through using one, it’ll drop all the way when you deactivate.
• You have to upgrade the ability to move from two gauges to four.
• As noted in the Healing section, you can use your “Limit Break” to recover HP.
• Triggering a “Limit Break” can be used similarly to Rift Slip in the sense that it can interrupt lengthy recovery animations. A good opportunity to make use of this feature is after having used Dancing Steel or Lv. 5 “Zantetsuken.”