The final boss of a video game stands for the last and greatest challenge of a stage of life. Dream books read facing it as readiness to confront what has been looming.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.