Court of Vantress

• WWizards of the Coast2023-09-01
  Official Ruling
  When Court of Vantress becomes a copy of a permanent, it's neither entering nor leaving the battlefield. Any enters-the-battlefield or leaves-the-battlefield abilities won't trigger.
• WWizards of the Coast2023-09-01
  Official Ruling
  The game starts with no monarch. As a player becomes the monarch, the current monarch (if any) ceases being the monarch. There is never more than one monarch at a time.
• WWizards of the Coast2023-09-01
  Official Ruling
  There are two inherent triggered abilities associated with being the monarch. These triggered abilities have no source and are controlled by the player who was the monarch at the time the abilities triggered. The full texts of these abilities are "At the beginning of the monarch's end step, that player draws a card" and "Whenever a creature deals combat damage to the monarch, its controller becomes the monarch."
• WWizards of the Coast2023-09-01
  Official Ruling
  Court of Vantress copies the printed values of the enchantment or artifact plus any copy effects that have been applied to it.
• WWizards of the Coast2023-09-01
  Official Ruling
  If the triggered ability that causes the monarch to draw a card goes on the stack and a different player becomes the monarch before that ability resolves, the first player will still draw the card.
• WWizards of the Coast2023-09-01
  Official Ruling
  If the monarch leaves the game during another player's turn, that player becomes the monarch. If the monarch leaves the game during their turn, the next player in turn order becomes the monarch.
• WWizards of the Coast2023-09-01
  Official Ruling
  If the copied permanent is copying something else, then the token enters the battlefield as whatever that permanent copied, with the stated exceptions.
• WWizards of the Coast2023-09-01
  Official Ruling
  If combat damage dealt to the monarch causes that player to lose the game, the triggered ability that causes the controller of the attacking creature to become the monarch doesn't resolve. In most cases, the controller of the attacking creature will still become the monarch as it is likely their turn.
• WWizards of the Coast2023-09-01
  Official Ruling
  Any enters-the-battlefield abilities of the copied permanent will trigger when the token enters the battlefield. Any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities of the permanent will also work.
• WWizards of the Coast2023-09-01
  Official Ruling
  The copy effect lasts indefinitely. Often, it will last until it is overwritten by another copy effect (if it copies another permanent on a future turn, perhaps).
• WWizards of the Coast2023-09-01
  Official Ruling
  If the copied permanent has in its mana cost, X is 0.
• WWizards of the Coast2023-09-01
  Official Ruling
  If Court of Vantress becomes a copy of a token, it copies the original characteristics of that token as defined by the effect that put it onto the battlefield. It won't become a token.
• WWizards of the Coast2023-09-01
  Official Ruling
  If another permanent becomes a copy of Court of Vantress, it will become a copy of whatever Court of Vantress is currently copying (if anything) that also has Court of Vantress's last ability.
• WWizards of the Coast2023-09-01
  Official Ruling
  If Court of Vantress becomes a copy of an Aura, it's put into its owner's graveyard unless it's somehow attached to an appropriate object or player already. If it becomes a copy of an Equipment and is attached to a creature, it'll become unattached when it becomes a non-Equipment, non-Aura permanent.
• WWizards of the Coast2023-09-01
  Official Ruling
  The token copies exactly what was printed on the original permanent and nothing else (unless that permanent is itself copying something else; see below). It doesn't copy whether that permanent is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.

Rulings via Scryfall