Court of Ambition — ruling 1

As Court of Ambition's second ability resolves, first the next opponent in turn order chooses whether they are discarding or not. If they are, they choose a card without revealing it (or two cards without revealing them, if you're the monarch), then each other opponent in turn order does the same. Then each chosen card is discarded simultaneously, and finally each player who couldn't or didn't discard loses the appropriate amount of life.

Court of Ambition — ruling 2

The game starts with no monarch. Once an effect makes one player the monarch, the game will have exactly one monarch from that point forward. As a player becomes the monarch, the current monarch (if any) ceases being the monarch.

Court of Ambition — ruling 3

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."

Court of Ambition — ruling 4

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.

Court of Ambition — ruling 5

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.

Court of Ambition — ruling 6

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.

Court of Ambition : règles, fonctionnement et interactions (MTG)

Court of Ambition 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

When this enchantment enters, you become the monarch. At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

How it works : Court of Ambition

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
As Court of Ambition's second ability resolves, first the next opponent in turn order chooses whether they are discarding or not. If they are, they choose a card without revealing it (or two cards without revealing them, if you're the monarch), then each other opponent in turn order does the same. Then each chosen card is discarded simultaneously, and finally each player who couldn't or didn't discard loses the appropriate amount of life.
Card named in this ruling
The Monarch
#2November 10, 2020· Wizards of the Coast
The game starts with no monarch. Once an effect makes one player the monarch, the game will have exactly one monarch from that point forward. As a player becomes the monarch, the current monarch (if any) ceases being the monarch.
Card named in this ruling
The Monarch
#3November 10, 2020· Wizards of the Coast
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."
Card named in this ruling
The Monarch
#4November 10, 2020· Wizards of the Coast
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.
Card named in this ruling
The Monarch
#5November 10, 2020· Wizards of the Coast
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.
Card named in this ruling
The Monarch
#6November 10, 2020· Wizards of the Coast
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.
Card named in this ruling
The Monarch