Why mill your opponent out of cards with countless spells when it can be done in one turn with two cards leaving room for other win strategies. {leyline of the void} + {helm of obediance} if there are any doubts, it has been tried and tested many times on magic online where all rules are implemented properly, by yours truly. It is a joyful experiance. You simply target your opponent with the helm tapping only one mana and the whole deck is gone because no card ever makes it into the graveyard.
Very Nice!
Note that this works because of the Void's replacement effect. This wouldn't work with {Planar Void}, since the cards do go to the graveyard first. When I saw this, I was hoping that it would work with {Thought Dissector} too, since it's a similar effect to the Helm. Sadly they changed the wording. :'(