The setup for the sermons is almost complete. What remains is the command to begin to preach. The command to preach repentance or coming destruction is reiterated. It is also commanded that Amulek go with him. The Lord, therefore, provides Alma with the second witness that will be needed to provide divine justice upon a people should they not repent.
Mormon gives away some of the ending of the story by indicating that while Alma and Amulek might be imprisoned, they could not be confined nor slain. Those events will be discussed before Mormon finishes with the story of Ammonihah.