What does Ashiok, Nightmare Weaver do?
user
[+2]: Exile the top three cards of target opponent's library.\n[−X]: Put a creature card with mana value X exiled with Ashiok, Nightmare Weaver onto the battlefield under your control. That creature is a Nightmare in addition to its other types.\n[−10]: Exile all cards from all opponents' hands and graveyards.
assistant