Shelldock Isle — ruling 1

"Hideaway N" means "When this permanent enters the battlefield, look at the top N cards of your library. Exile one of them face down and put the rest on the bottom of your library in a random order. The exiled card gains 'The player who controls the permanent that exiled this card may look at this card in the exile zone.'"

Shelldock Isle — ruling 2

Any player who has controlled a permanent with a hideaway ability since a card was exiled with it may look at that card.

Shelldock Isle — ruling 3

Previously, permanents with hideaway entered the battlefield tapped. This ability has been removed from the definition of hideaway. Older cards have received errata to have an additional paragraph that reads "[This permanent] enters the battlefield tapped," and they now have hideaway 4.

Shelldock Isle — ruling 4

Hideaway now causes you to put the rest of the cards on the bottom of your library in a random order instead of any order.

Shelldock Isle — ruling 5

It doesn't matter which library has twenty or fewer cards in it, and you don't have to specify a library.

Shelldock Isle : règles, fonctionnement et interactions (MTG)

Shelldock Isle is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.) This land enters tapped. : Add . , : You may play the exiled card without paying its mana cost if a library has twenty or fewer cards in it.

How it works : Shelldock Isle

Original English text — Wizards of the Coast / Scryfall

#1April 29, 2022· Wizards of the Coast
"Hideaway N" means "When this permanent enters the battlefield, look at the top N cards of your library. Exile one of them face down and put the rest on the bottom of your library in a random order. The exiled card gains 'The player who controls the permanent that exiled this card may look at this card in the exile zone.'"
No other card is named in this ruling.
#2April 29, 2022· Wizards of the Coast
Any player who has controlled a permanent with a hideaway ability since a card was exiled with it may look at that card.
No other card is named in this ruling.
#3April 29, 2022· Wizards of the Coast
Previously, permanents with hideaway entered the battlefield tapped. This ability has been removed from the definition of hideaway. Older cards have received errata to have an additional paragraph that reads "[This permanent] enters the battlefield tapped," and they now have hideaway 4.
No other card is named in this ruling.
#4April 29, 2022· Wizards of the Coast
Hideaway now causes you to put the rest of the cards on the bottom of your library in a random order instead of any order.
No other card is named in this ruling.
#5October 1, 2007· Wizards of the Coast
It doesn't matter which library has twenty or fewer cards in it, and you don't have to specify a library.
No other card is named in this ruling.