Coram, the Undertaker

Eminence — During each of your turns, if Coram is in
the command zone or on the battlefield, you may play a
land and cast a spell from among cards in graveyards that
were put there from libraries this turn.

Coram gets +X/+0, where X is the greatest power among
creature cards in all graveyards.

Whenever Coram attacks, each player mills a card.