A lot of non human enemies and their variances. The Malboros are the biggest threat in the fight because of "bad breath" ability. They have increased chance to inflict toad status, which is already bad, but petrify can essentially kill your units right away.
Prioritize the Malboros before they get their turn. Bad breath is an area attack so make sure not to get close to your tank if you are not able to finish them off early. The rest of the enemies are fairly easy to deal with.
Malboros are weak to magic, skeletons to strike, and behemoth to missile.