Our Lady Underhound

Indestructable
As long as your devotion to black and green
is less than eight, Our Lady Underhound
isn't a creature.
Whenever a Dog or Human enters or leaves your graveyard,
create a Food token named "Treat".
{1}{g}{b}{b}, Sacrifice a Food: Mill 2 cards,
then exchange target land you control
with target permanent card in your graveyard.