Reflected more than 1000 bullets while in Phantom form.
From the Origin menu screen, navigate downwards and enter "settings". From there, enter "Game settings" and change your life to 1. This allows you to store more Phantom energy thus giving you a longer time to bounce bullets. I suggest not using novice mode due to there being less bullets. During the first half of the stage before the mid-boss, gain phantom energy by point blanking enemies whilst holding down . After defeating the mid-boss, enter phantom mode with and run into all bullets and don't destroy enemies. The achievement will unlock very shortly.