If you use it for the volley then it is discarded. If you choose to do a heroic sacrifice with it instead then you get the die roll modifier for the rest of the game versus your medium and long range volleys. You do get -5 points at the end of the game when using the heroic sacrifice keep in mind. This card and a few others are hard to get and use as you need to draw it before you fire your first volley in the game. So this usually means you need to draw it within the first 3-5 card. If you draw it after the first volley is fired then it is discarded as a wasted draw.