Booker's "anticipation stage" is defined by the restlessness of the hero, and that's exactly what we see in Faustus as he sits in his study considering, then rejecting, various academic disciplines as useless and not worth his time. Faustus needs a discipline he perceives as worthwhile at which he can direct his energies, and that's what magic gives him. As he tells Valdes and Cornelius, "Tis magic, magic that hath ravished me" (1.1.103), and Faustus's new direction is clear: he decides to become a great magician.
Once Faustus signs his pact with the devil, agreeing to grant him his soul in exchange for twenty-four years of life with Mephistopheles as his slave, he's pretty much done for. After all, a contract is a contract, and there are no takebacks with the devil.
Or are there? That's the question that will follow Faustus, and characters like the Good and Bad Angels, for the rest of the play. Does Faustus have to continue in sin now that he has fallen, or can he still repent and return to God?
Whatever the answer to this question, things seem to be going well for Faustus at first. He gains power, wealth, acclaim, and the answers to most of his questions about the nature of the universe.
When the Old Man appears, he's a threat to Faustus because he questions the choice Faustus has made and tells him there's still a chance for him to make a different, better one. Faustus appears not to heed the Old Man's advice, but when he confesses what he has done to the Scholars, he's not exactly proud of his choice. Faustus now appears to realize that he has made the wrong decision in giving his soul to the devil (uh, dude, we could have told you that). But as hard as he tries, he can't feel true repentance. He knows, then, that there is no hope for him anymore.
Even though the forces of the devil are closing in on him, Faustus still fights the inevitable. He calls on Christ, but it's too late for that. Barring heaven, he hopes that his soul will disappear or be reincarnated in a beast so that he doesn't have to suffer the torments of hell. His agony and dread are horrible, extreme, and seem like they might never end.
But end they do, when the devils enter Faustus's study to carry his soul to hell. Let's be honest: Faustus's damnation is entirely his own fault. It was he, after all, who signed the pact with the devil, and he who refused to repent of it despite the assurances of several different characters that God would forgive him. Now, the forces Faustus has unleashed close in on him and bring about the end that was inevitable from the beginning. It's true what they say: you reap what you sow.