I just re-read this Navigator power from Into the Storm, and I suddenly realized that it's confusing the hell out of me. When are you supposed to perform this action? I see several options: (I'm limiting this to giving a bonus to BS for simplicity)
1) Before any shots are fired. If this is the case, when do you decide which attack gets the bonus? Do you give the bonus before or after BS is rolled, risking wasting the entire bonus if the attack misses?
2) After a successful attack but before rolling for damage? This seems like the best option from a gameplay perspective, but carries its own potential problems, among other things from a fluff perspective.
3) None of the above (explain!).