The Raven Queen

When The Raven Queen enter the battlefield.
Create a number of 1/1 black Bird creature tokens
with flying equal to your devotion to black.
Whenever a creature is put into an opponent's
graveyard from anywhere, create a 1/1 black
Bird creature token with flying.
Whenever a bird you control dies, each
opponents put the top card of their library
into their graveyard.