Tom's elaborate plans can be seen as merely a child's imagination filled eith incidents from books. However, Twain makes a pointed attack in this planning. Where is it directed? -chapter 35

This is directed at Tom. For all of Tom's impish qualities, he cares little for Jim. By now we have gotten to know Jim as one of the most, if not the most, sympathetic characters in the book. Tom's childish plan is dangerous for all involved, especially for Jim.