Complex sentence: The Halloweentown students (a witch, a warlock, a werecat, a werewolf, an ogre, a pink troll, a fairy, a zombie and a gremlin) arrive, magically given human appearances to disguise their true non-human natures.
Split into simpler sentences: The Halloweentown students consisting of a witch, a warlock, a werecat, a werewolf, an ogre, a pink troll, a fairy, a zombie and a gremlin arrive. They are magically given human appearances to disguise their true non-human natures.