Aether Nexus

Shroud
Whenever a player casts a spell from their hand, that player exiles the top X cards of their library, where X is twice that spell's converted mana cost.
Players may put card exiled with Aether Nexus into their hand by paying its converted mana cost and exiling the top card of their library.
If a player would exile cards from their library when they have no cards in their library, they win the game