Earn Espers
FFXII features 13 espers that you can acquire and assign to the characters on your team. Five of the espers are required, and you earn them through mission completion. The remaining eight espers are optional, and you earn them through side-quest discovery. To wield an esper as a power, you must first defeat it in battle. It will then appear on the skill book as a character to be assigned.
Assign Espers
You can Every assign espers only to one character, so you must plan out who will receive each esper before your commit. No defined "best" allotment of espers exists, but you should consider several key points. Assign at least one esper to each character because it is not beneficial to load all of the espers onto one or two characters. Split up Belias, Mateus, Adrammelech and Zalera among your four most magic-oriented characters.
Battle Speed
Battle speed is a game setting that you can alter by using the in-game options menu. Altering battle speed allows you to play the game at a slower pace, which helps players who struggle with the rapid-fire decisions on high speed. Espers remain active for only 90 seconds, so as your espers grow strong enough to last through their entire summon period, you should play at a high speed to maximize the number of attacks the Esper can cast before wearing out.
Final Attacks
Each esper has a unique final attack that you can trigger when it is defeated or its time runs out. In some instances, however, triggering a final attack requires you to meet certain criteria. Early in the game, don't worry about meeting these criteria because the benefit of the final attack over standard attacks is minimal. Later in the game, however, some espers have the ability to break the 9,999 damage cap, a highly useful skill. Shemhazai's Soul Purge can deal 60,000 damage, and Exodus' Meteor has the potential to randomly deal 30,000 damage. Zeromus' Big Bang deals five times as much damage as he has taken while summoned, and Zodiark's Final Eclipse deals 50,000 damage.