The Nameless Assassin

The Nameless Assassin cannot be blocked.

Whenever The Nameless Assassin deals damage to
an opponent, the defending player mills X cards
from the top of their library where X is the number
of Wolf creatures you control. The Nameless
Assassin may copy an ability from a creature in an opponent's graveyard in addition to this card's own abilities until the end of your turn. You may only
use this once per turn.