Millicent's Sisters

Whenever Millicent's Sisters deals combat damage
to a player, you may put a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counters on a creature, create a 1/1 green Insect creature token
with reach.

Rot for the scarlet goddess. O scarlet blossoms, flourish in distant lands, and return to us, the unwanted children.