Calvin, Newly Born

When Calvin, Newly Born enters the battlefield,
you may discard a card or sacrifice a creature,
then draw a card.
At the beginning of each player's upkeep, if you
have three or more creature cards in your
graveyard, sacrifice Calvin, Newly Born, then
search your graveyard, hand, and library for
Calvin, Martian Menace, then put it onto the
battlefield.