Its power allows Rohan to view a person's memories as if he were reading a book made from their body. Rohan can write commands in this book, which the target will unconsciously obey. He can also tear out a page, erasing the memories contained on it from the target's mind. He can't use his Stand to read his own "pages", but can use to write commands on them.
Its namesake is the Bob Dylan song "Knockin' on Heaven's Door".