Grafdigger's Cage and GSZ

[MSC]

Hi,
if I understand it correctly, Grafdigger's Cage prevents a creature from being "fetched" by Green Sun's Zenith.

But as I see it, it doesn't prevent a player from playing GSZ. So what happens to the creature the player searched for? Is it just shuffled back into the library?

[I am the brainwasher]

AFAIK the Spell is normally put on the stack and when it resolves it has no effect besides beeing shuffled back in. You could also fail to find anything at all even without Grafdigger's Cage so there is no countered on resolution or anything happening here.
Just a pretty useless manasink.

[Koby]

brainwasher is correct. Any attempt to put a creature into play would have to be rewinded to prevent it from happening. GSZ under Grafdigger's Cage has no effect other than shuffling your library twice.

[Malchar]

You simply do everything printed on the zenith that you're still allowed to do.

1. Search your library for a green creature with converted mana cost X or less.
2. Shuffle your library.
3. Shuffle the zenith into your library.

You still get to look through your library, but the creature you find will be shuffled away. You don't reveal it. (You don't even have to find something and you still get to look).

[John Cox]

What would happen with Oath of Druids ? You can't fail to find a creature there. Would the creature end up as your top card, or be shuffled away?

[Koby]

What would happen with Oath of Druids ? You can't fail to find a creature there. Would the creature end up as your top card, or be shuffled away?

You would do everything stated on the card except put it onto the battlefield.

1. Reveal card by card until a creature card would be revealed.
2. Attempts to put creature card into the battlefield. FAILS due to Grafdigger's Cage. The card remains on top of your library.
3. The remainder of the cards revealed are put into the graveyard.

[Koby]

Oath of Druids
Enchantment, 1G
At the beginning of each player's upkeep, that player chooses target player who controls more creatures than he or she does and is his or her opponent. The first player may reveal cards from the top of his or her library until he or she reveals a creature card. If he or she does, that player puts that card onto the battlefield and all other cards revealed this way into his or her graveyard.

Clarification on Grafdigger's Cage:
1/22/2011*: If a creature card tries to enter the battlefield from a graveyard or library, it stays in its current zone.

*Verbatim from Gatherer. Yes, they didn't update the year to 2012. We've always knows they were backwards.

Since Grafdigger's Cage doesn't effect revealing cards, you would reveal until you get to a creature. Then, the creature would remain in its current zone (top of the library), and the remaining cards would be binned.