ADEPTUS ASTARTES BATTLELINE units from your army:
Each time an ADEPTUS ASTARTES BATTLELINE unit from your army is selected to attack, after resolving those attacks, select one enemy unit hit by one or more of those attacks. Until the end of the turn, that enemy unit is auspex scanned. Each time an ADEPTUS ASTARTES model from your army makes an attack that targets an auspex scanned unit, re-roll a Hit roll of 1.