Boss: Professor Kou and Knight Avei (Professor Kou Spawns them during the fight)
Professor Kou's Info:
Attacks: Servant Call, High Dark Bolt, EX Pandemonium
Knight Avei's Info:
Attacks: Protection, HP Drain, High Barrier
To get this use Raigar, Karin, Astuma, and another strong golem. Have atsuma attack Kou and the others kill the Knight Avei. After that one's dead on the second turn, use your new EX move on Kou and have everyone else attack him. He will summon another Knight Avei but only attack Kou and use Karin's healing ability (and her EX move at the begenning of the fight on Kou and the Knight Avei) and Raigar's shield on the people he can and you'll win getting this achievement.