Wraithcaller

If you've expended black or green mana this turn,
create a black and green Mistwraith token with
ephemeral and "Mistwraith's power and
toughness is equal to the number of creatures in
your graveyard" when Wraithcaller enters.
(Creatures with ephemeral do not enter with
summoning sickness. However, they will
self-destruct at the end of the turn.)

She appears without a sound. The terrors that follow her are far less subtle.