Cruel Bladeswoman

Fulgrim's scions are renowed for their bladecraft,
toying with their inferiors while preparing an
exquisite, penetrating thrust.
Use this Stratagem in the Fight phase, when an
Emperor's Children unit from your army
is selected to fight. Until the end of the phase,
each time a Heretic Astartes model in that
unit makes a melee attack, improve the Armor
Penetration characteristic of that attack by 1.