Which card wins?

[Anoobass]

If player A has a  {Leyline of the Void} out and player B mills  {Progenitus}, what happens, which card would win?

[5/9 Turtle]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

[Keyeto]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

[scarsabrex]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

Actually leyline is also a replacement effect. Progenitus will go wherever its owner chooses.

[Anoobass]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

But leyline also states it the same way, if it would hit the graveyard, exile it instead

[Anoobass]

Would it more depend on which players turn that the triggers were set off so he/she could decide which goes off first?

[scarsabrex]

Would it more depend on which players turn that the triggers were set off so he/she could decide which goes off first?

Nah, when two replacement effects contradict each other, the controller of the card chooses which applies, if there is no controller than the owner chooses.

[Fricker13]

They both state "if he would be" therefore one has to somehow have priority and the other fizzle. How to determine that I don't know.
Define controller and owner plz.

[Anoobass]

Controller of the card would be the person with progen on his side of the battlefield, owner is the person who has the card, in this case Player B, if I am correct.
There is no controller in this situation, therefor the owner (player B) would decide if Scarsabrex is correct.

[MisterJH]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

Actually leyline is also a replacement effect. Progenitus will go wherever its owner chooses.

But the card must be able to hit the GY. {progenitus} never has the ability, he will never be effect by leyline. I believe its {kozilek butcher of truth} that is shuffled AFTER it hits GY? Well anyways, the card im thinking of will be exiled.

Well, thats my logic.

[Anoobass]

Though leyline doesn't say if it hits the GY exile, both cards state "if *INSERT CARD HERE* would be, instead do..."

Same wording with 2 different endings.
Darn you WotC, why do make me think so much...

[Anoobass]

Well, time for work, going to drive me crazy till I see a resolved stamp.

Good luck,
Anoobass.

[Kaleo42]

616.1e: Once the chosen effect has been applied, this process is repeated (taking into account only replacement or prevention effects that would now be applicable) until there are no more left to apply.
Example: Two permanents are on the battlefield. One is an enchantment that reads "If a card would be put into a graveyard from anywhere, instead exile it," and the other is a creature that reads "If [this creature] would be put into a graveyard from the battlefield, instead shuffle it into its owner's library." If the creature is destroyed, its controller decides which replacement to apply first; the other does nothing.

This is true for alara's great honey badger but not for zendikar's spaghetti gods. Reason being is the spaghetti gods say "when" not "if" which means it is a trigger not a replacement effect.
RESOLVED

[Keyeto]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

But leyline also states it the same way, if it would hit the graveyard, exile it instead

This is true. Although Progenitus can never hit the grave, technically there are two replacement effects going head to head. Whoever controls Progenitus will choose which replacement effect to apply first:

616.1.: If two or more replacement and/or prevention effects are attempting to modify the way an event affects an object or player, the affected object's controller (or its owner if it has no controller) or the affected player chooses one to apply, following the steps listed below. If two or more players have to make these choices at the same time, choices are made in APNAP order (see rule 101.4).

[Kaleo42]

Progenitus, it says  that it's shuffled into your library instead of putting it into the graveyard

This is correct. {Progenitus} has a replacement effect that sends him to the library instead of the graveyard when he "dies." The Leyline will never trigger, since Progenitus never hits the grave.

But leyline also states it the same way, if it would hit the graveyard, exile it instead

This is true. Although Progenitus can never hit the grave, technically there are two replacement effects going head to head. Whoever controls Progenitus will choose which replacement effect to apply first:

616.1.: If two or more replacement and/or prevention effects are attempting to modify the way an event affects an object or player, the affected object's controller (or its owner if it has no controller) or the affected player chooses one to apply, following the steps listed below. If two or more players have to make these choices at the same time, choices are made in APNAP order (see rule 101.4).

Haha! Beat you to it