The battle against Scarmiglione takes place on Mt. Ordeals, and comes in two phases. In the first, he is flanked by four Skullnants, who must be defeated before the party can touch him. As an undead entity, Scarmiglione is weak against fire magic and cure spells.
During the second phase, Scarmiglione is much more powerful, and attacks your party from behind with powerful physical attacks that can cause poison.