Fall from Favor

• WWizards of the Coast2020-11-10
  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 Coast2020-11-10
  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 Coast2020-11-10
  Official Ruling
  If the target creature is an illegal target by the time Fall from Favor tries to resolve, it doesn't resolve. It won't enter the battlefield, so its enters-the-battlefield ability won't trigger.
• WWizards of the Coast2020-11-10
  Official Ruling
  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.
• WWizards of the Coast2020-11-10
  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 Coast2020-11-10
  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.

Rulings via Scryfall

• WO
  Wizards of the Coast2021-01-14

  Fall from Favor was banned in pauper on January 14, 2021. Magic Online league data and tournament results for the Pauper format have shown that the recent addition of Fall from Favor is having an adverse effect on the metagame. Serving as both a creature removal tool and a card advantage engine, Fall from Favor pushes out aggressive creature decks and places too much emphasis on a player becoming and remaining the monarch before opposing decks can prepare counterplay. To create more space in the metagame for aggressive decks that punish slower decks and reduce the importance of the monarch mechanic early in the game, Fall from Favor is banned in Pauper. Source: https://magic.wizards.com/en/news/news/january-14-2021-banned-and-restricted-announcement