Ya'roshh, Thundering Roar

This creature gets +1/+1 for each Zombie
in each GY. On your turn, other creatures
become only Zombies (battlefields and GYs ).
{w}{b}{g}{t}: Create a 3/3 Black Zombie
token with wither and firststrike.
{2}{w}{b},{t}, sacrifice a land and a non-token
creature: Search for a card, and put it in
your hand, then shuffle.
{u/b}{t}, sacrifice a creature and discard a card:
Destroy target non-land permanent and
everyone mills 1.