Plague Banner

Use this Stratagem before the battle.
Choose one of your NURGLE models with a
Daemonic Icon.
That icon is upgraded to a Plague Banner. In
addition to its normal ability, the power of the
banner can be used once per battle, just before
the bearer's unit fights. When used, increase the
Damage characteristic of all plagueswords carried
by the bearer's unit to 2 until end of the phase.