Agregor, Hive Recruiter

{b}, Reveal Agregor, Hive Recruiter from your
hand: Put a parasite counter on target creature
card in an opponent's graveyard. Activate only
during your turn.
When Agregor enters the battlefield, exile each creature card in your opponents graveyard with
a parasite counter on it, then create a 1/1 black Parasite creature token with haste, for each
creature exiled by Agregor.