Grave-Bound Mercenary

Bounty Hunt (When this creature enters the
battlefield, put a bounty counter on target creature. For as
long as that creature is on the battlefield, its controller
can't control three or more creatures.)
Grave-Bound Mercenary's power is equal to the
number of creatures in your opponents
graveyards.
If Grave bound mercenary's power is higher than its
toughness, it has undying.