Coram, the Undertaker (Modern Horizons 3 Commander)

Legendary Creature Ñ Human Warrior - Coram gets +X/+0, where X is the greatest power among creature cards in all graveyards.
Whenever Coram attacks, each player mills a card.
During each of your turns, you may play a land and cast a spell from among cards in graveyards that were put there from libraries this turn.