, : Target opponent mills a card, then repeats this process until a creature card or X cards have been put into their graveyard this way, whichever comes first. If one or more creature cards were put into that graveyard this way, sacrifice Helm of Obedience and put one of them onto the battlefield under your control. X can’t be 0.
If an effect like that of Leyline of the Void prevents cards from being put into your opponent’s graveyard, the process described in the first sentence of Helm of Obedience’s effect will never stop. Your opponent’s entire library will be exiled, even if X is 1.
01-10-2008
wotc
You put the creature card onto the battlefield even if you can’t sacrifice Helm of Obedience (because it’s left the battlefield by the time its ability resolves, for example).
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.
, 
: Target opponent mills a card, then repeats this process until a creature card or X cards have been put into their graveyard this way, whichever comes first. If one or more creature cards were put into that graveyard this way, sacrifice Helm of Obedience and put one of them onto the battlefield under your control. X can’t be 0.
