Night Stalker

As mentioned by the description, these enemies are impervious to all sorts of physical-based attacks and skills, making quite a large annoyance to deal with. Due to their high stats, they are also hard to take down, forcing the player to use attack items, Song Magic, and skills and weapons that can deal elemental damage in order to defeat them. Aside of this, they can also Curse and Paralyze the party, and their Running Fire skill is a Lv. 2 Stored Attack, so whenever you encounter these enemies, fight cautiously.