Ashiok, Delver of Minds

: Whenever one or more cards leave a graveyard, put that many loyalty counters on Ashiok, Delver of Minds.
-2: Exile a card from a graveyard. Put X 2/1 black Nightmare token with menace onto the battlefield, where X is the exiled card’s mana value.
-X: Target player mills triple X cards. Put up to X milled enchantment and creature cards milled this way onto the battlefield under your control.