Have your party at level 56; no more, no less. Save at Terminus 7 Adjunct before the fight. There are a few things in this battle that make it more difficult. First of all, there is a 5:00 minute timer. If you do not defeat Zalera before the time runs out, you must start again. You also cannot use Espers when there are undead in the area. Finally, he can cast status effects on you based on your level; 2-5 are the ones he can do so on, and he can also use status effects on you if you have a prime number for a level. To begin the fight, dispel the Boss. If there are undead in the area, get everyone to attack them. When his HP starts to get low, he will start to cast Sleepga, Stop, and Death, no matter what level you are near. Near the end, use a Quickening chain to finish this long fight and get the Esper.