Ninaza, Angel of Misfortune

Flying, infect (This creature deals damage to
creatures in the form of -1/-1 counters and to players
in the form of poison counters.)
Whenever a -1/-1 counter is put onto a creature
an opponent controls, you gain 1 life.
Whenever one or more poison counters are put
onto an opponent, that player discards a card
and you draw a card.