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 the end of the
phase