Strike from the Shadows

{t}One ADEPTUS ASTARTES INFANTRY
unit from your army that has not been selected
to shoot this phase.
Until the end of the phase, each time a model in
your unit makes a ranged attack that targets an
enemy unit that is more than 12" away, improve
the BS and AP characteristics of that attack by 1.
If one or more enemy models are destroyed as a
result of those attacks, select one of those
destroyed models; that destroyed model’s unit
must take a Battle-shock test.