Archon of Coronation — ruling 1

While Archon of Coronation's last ability applies, damage dealt to you still has all effects other than causing you to lose life. For example, abilities that trigger on that damage being dealt still trigger; if the source has lifelink, its controller still gains life; and so on.

Archon of Coronation — ruling 2

Combat damage dealt to you by a commander is still tracked, even if it didn't cause you to lose life.

Archon of Coronation — ruling 3

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.

Archon of Coronation — ruling 4

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."

Archon of Coronation — ruling 5

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.

Archon of Coronation — ruling 6

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.

Archon of Coronation — ruling 7

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.

Archon of Coronation : règles, fonctionnement et interactions (MTG)

Archon of Coronation 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

Flying When this creature enters, you become the monarch. As long as you're the monarch, damage doesn't cause you to lose life. (When a creature deals combat damage to you, its controller still becomes the monarch.)

How it works : Archon of Coronation

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
While Archon of Coronation's last ability applies, damage dealt to you still has all effects other than causing you to lose life. For example, abilities that trigger on that damage being dealt still trigger; if the source has lifelink, its controller still gains life; and so on.
No other card is named in this ruling.
#2November 10, 2020· Wizards of the Coast
Combat damage dealt to you by a commander is still tracked, even if it didn't cause you to lose life.
No other card is named in this ruling.
#3November 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
#4November 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
#5November 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
#6November 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
#7November 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