Gaza (ガゼール, Gazeru, lit. "Gazelle") is fought twice in Legend of Legaia. He is battled in a different form the second time due to morphing with the power of a Sim-Seru given to him by Songi.
The first battle with Gaza takes place on the top of Sol Tower after the Ra-Seru heroes receive the Genesis Seedling from Old Deez. Gaza wishes to prevent the heroes from driving away the Mist as it will take away his reason for living, which is to perfect his swordsmanship by killing the Seru in the lower levels of the tower.
Gaza can prove to be a fairly difficult boss. He only has two attacks, the first being a physical combo for up to 6 hits that can do 700+ damage to a single character as well as a special attack called Astral Slash, which can do over 1,200 damage to a single character - luckily this attack can be completely blocked.
Gaza's element is Light, and as such equipping party members with available Luminous Jewels is a good idea in order to lessen the damage from his attacks (Noa should equip the Luminous Jewel in any circumstance where it is available considering she is most likely to get knocked out from Gaza's attacks). Defender Chains can be a lifesaver in this battle as well, as it will increase the probability of blocking his fatal special attack. Equipping Noa with an HP boosting accessory is also recommended. Noa should have 9 art blocks by this battle and her miracle art Noa's Ark should be used whenever she has enough AP in order to execute it.
Vahn should attack primarily with the Kemaro spell if he has absorbed it and with physical combos if his MP is depleted or if he does not have the Kemaro spell. Gala should be designated the primary healer and given the Speed Chain to guarantee he will go first in battle. The Speed Chain will be obtained from the Disco King in the Sol Fever Disco if Noa obtains over 500 points in the dance tutorial.