Complex sentence: There are several references to the original "The Warlock of Firetop Mountain", which includes a case that housed an arrow in the original book is found to be empty and a trap involving a sword disguised as a lever also reappears.
Split into simpler sentences: There are several references to the original "The Warlock of Firetop Mountain", including a case that housed an arrow in the original book that is found to be empty. A trap involving a sword disguised as a lever also reappears.