Death, the Fourth Knight

Flying, Deathtoutch.
When Death, the Fourth Knight enters the
battlefield, you may put a creature of your
graveyard into the battlefield on your control.
In each end of step, if an opponent lost life
this turn, you may put a creature of your
graveyard into the battlefield on your control.
If you don't, create a 2/2 black Zombie
creature token.