Bloodthirsty Darkwing

Flying
Manaleech {b}{b}(Whenever an opponent activates an ability of a creature, you may pay {b}{b}. If you do, draw a card unless that player puts a -1/-1 counter on that creature.)
Whenever a -1/-1 counter is put on a creature, Bloodthirsty Darkwing gets +1/+0 and lifelink until the end of turn.