MTG >Combos >Leyline of the Void +Helm of Obedience +

Leyline of the Void's ability creates a replacement effect that causes all cards that went to the graveyard to be exiled instead. With both in play, activate Helm of Obedience's ability with an X of at least 1. Helm of Obedience will mill the opponent's cards until X cards are put into the graveyard, but as the cards are going into exile instead of the graveyard, there will never be X cards in the graveyard. Therefore, Helm of Obedience will exile the entire opponent's library.