Collector's Cage

• WOTC Official Reminder Textofficial rules
  Hideaway — When this permanent enters the battlefield, look at the top N cards of your library. Exile one face down and put the rest on the bottom in any order.

• WWizards of the Coast2024-04-12
  Official Ruling
  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.
• WWizards of the Coast2024-04-12
  Official Ruling
  If the spell you cast has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
• WWizards of the Coast2024-04-12
  Official Ruling
  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.
• WWizards of the Coast2024-04-12
  Official Ruling
  Collector's Cage's last ability looks at the creatures you control as it resolves to determine if you can play the exiled card. For example, if you control a 4/5 creature, a 1/1 creature, and a 2/1 creature, there are three different powers among creatures you control.
• WWizards of the Coast2024-04-12
  Official Ruling
  If you cast a spell "without paying its mana cost," you can't choose to cast it for any alternative costs. You can, however, pay additional costs, such as kicker costs. If the spell has any mandatory additional costs, those must be paid to cast the spell.
• WWizards of the Coast2024-04-12
  Official Ruling
  Any player who has controlled a permanent with a hideaway ability since a card was exiled with it may look at that card.
• WWizards of the Coast2024-04-12
  Official Ruling
  You choose whether to play the exiled card as Collector's Cage's last ability resolves. If you do, you do so as part of the resolution of that ability. You can't wait to play it later in the turn. Timing restrictions based on the card's types are ignored. However, you can never play lands on other players' turns.

Rulings via Scryfall