My strategy attack like crazy and use life to conserve mp or use a phoenix down on your fallen dudes or dudetts. If you have two or more with little hp use a megaelixer or (elixer if you don't have enough on each separately). Don't heal instead use Holy with Rosa and Porom(use reflect if nessecery). When he count down that means you've been fighting him for some time. Think of the brachy>like this his the lunar bahamut and if you don't finish him off fast your dead. da point>HE IS LESS LIKELY TO ATTACK IF YOU ATTACK ALOT BUT WILL STILL USE GLAREdarn
i also got four hero's shield and did this 3 times without kain using the tornado thing. I deafeated him at lv's 60 something 2x at lv's 80 somthing and the last time when my party was was all at lv's 97-99.