Arsene, Shadow Lurker

+1: Draw a card, then discard a card. If you discarded an instant or sorcery this way, exile that card with a shadow counter.
-2: You may cast a card exiled with a shadow counter for {2} less. If a card would enter the graveyard this way, exile it.
-5: Gain an emblem. "When you cast an instant or sorcery from exile, target player mills x cards. x is equal to the amount of cards you own in exile"