use fei (for system id), citan (because he's strong and fast), and maria (very strong, and doesn't need to learn death blow moves to have good gear attacks.) do the majority of damage with fei using system id, and just have citan and maria build up ap, trying to get them into infinity mode. once hammer flashes, you have 10 turns to do like 25000 to him, so lvl 3 hits or infinity hits are the best, but make sure that fei is on booster, and has at least 2 turns left in infinity mode.