Nyarlaphotep, the Black Man

Horror creatures get +1/+1
Whenever a Horror creature attacks, each player
loses 1 life and Cthulhu shuffles the first card
from its graveyard into its library.
When Nyarlathotep leaves the battlefield reveal
cards from the top of Cthulhu's library until a
legendary creature card is revealed, put that card
onto the battlefield, then shuffle the rest into
Cthulhu's library.