SUPER ROBOT WARS TAISEN OG SAGA - MASAU KISHIN - THE LORD OF ELEMENTAL

haii all... who can help me?? i'm stuck and can't finish at stage 18..at turn 10, i always gameover just same if i killed 3 last enemy ... can somebody help me??thanx

You have to kill those 3 enemies in one attack at the same time (AKA use a MAP attack)