Sunrise Cavalier — ruling 1

If it is day, and the active player of the previous turn cast no spells during their turn, it becomes night.

Sunrise Cavalier — ruling 2

If it is night, and the active player of the previous turn cast two or more spells during their turn, it becomes day.

Sunrise Cavalier — ruling 3

Before a player untaps their permanents during the untap step, the game checks to see if the day/night designation should change.

Sunrise Cavalier — ruling 4

If a triggered ability triggers whenever day becomes night or night becomes day, it only triggers if it was already either day/night and becomes the other. It does not trigger when the game becomes day or night for the first time.

Sunrise Cavalier — ruling 5

Day and night are designations that the game itself can have. The game starts as neither. Once the game becomes day (or less commonly, night), the game will be exactly one of them—day or night—going back and forth for the rest of the game.

Sunrise Cavalier : règles, fonctionnement et interactions (MTG)

Sunrise Cavalier 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

Trample, haste If it's neither day nor night, it becomes day as this creature enters. Whenever day becomes night or night becomes day, put a +1/+1 counter on target creature you control.

How it works : Sunrise Cavalier

Original English text — Wizards of the Coast / Scryfall

#1September 24, 2021· Wizards of the Coast
If it is day, and the active player of the previous turn cast no spells during their turn, it becomes night.
No other card is named in this ruling.
#2September 24, 2021· Wizards of the Coast
If it is night, and the active player of the previous turn cast two or more spells during their turn, it becomes day.
No other card is named in this ruling.
#3September 24, 2021· Wizards of the Coast
Before a player untaps their permanents during the untap step, the game checks to see if the day/night designation should change.
No other card is named in this ruling.
#4September 24, 2021· Wizards of the Coast
If a triggered ability triggers whenever day becomes night or night becomes day, it only triggers if it was already either day/night and becomes the other. It does not trigger when the game becomes day or night for the first time.
No other card is named in this ruling.
#5September 24, 2021· Wizards of the Coast
Day and night are designations that the game itself can have. The game starts as neither. Once the game becomes day (or less commonly, night), the game will be exactly one of them—day or night—going back and forth for the rest of the game.
No other card is named in this ruling.