The wall that connects reality from fiction. Breaking this could destroy the multiverse. It is what is keeping you alive right now. Breaking it allows you to travel to any universe. You could travel back to WW2 and be a certain figure in the war, or be a victim in the war. You could travel to a fictional universe like Harry Potter, and be a student at Hogwarts and learn all sort of spells! The fourth wall knows every universe and what happens in them. Every tv series, video game, book and movie.