Ashiok, Weaver of Woe

: Ashiok, Weaver of Woe costs 1 less for each Nightmare and/or Horror you control.
+1: Nightmares and Horrors you control get +1/+1 and whenever this creature deals combat damage to a player this turn. That player mills a card.
-9: All Creatures you control gain "Whenever this creatures deals combat damage, each opponent exiles 6 cards from their library or hand."