Devourer of Memory

Whenever one or more cards are put into your graveyard from your library, this creature gets +1/+1 until end of turn and can't be blocked this turn.
{1}{U}{B}: Mill a card.

Can't Wake Up

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Cruel Somnophage

Cruel Somnophage's power and toughness are each equal to the number of creature cards in all graveyards.

Cruel Somnophage // Can't Wake Up

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Mirko, Obsessive Theorist

Flying, vigilance
Whenever you surveil, put a +1/+1 counter on Mirko.
At the beginning of your end step, you may return target creature card with power less than Mirko's from your graveyard to the battlefield with a finality counter on it. (If it would die, exile it instead.)

Extract from Darkness

Each player mills two cards. Then you put a creature card from a graveyard onto the battlefield under your control.