Cheapest priced copy (Innistrad: Double Feature): $0.35 at Card Kingdom, near mint, their price list as of .
Celestus Sanctifier 
Creature — Human Cleric · 3/2 · Common · Innistrad: Midnight Hunt · #12
If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, look at the top two cards of your library. Put one of them into your graveyard.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Innistrad: Double Feature | 12 | Common | $0.35 | $0.49 |
| Innistrad: Midnight Hunt | 12 | Common | $0.35 | $0.49 |
6 rulings from Wizards of the Coast
- 24 September 2021If it is day, and the active player of the previous turn cast no spells during their turn, it becomes night.
- 24 September 2021The card you don't put into your graveyard stays on top of your library.
- 24 September 2021If it is night, and the active player of the previous turn cast two or more spells during their turn, it becomes day.
- 24 September 2021Day 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.
- 24 September 2021Before a player untaps their permanents during the untap step, the game checks to see if the day/night designation should change.
- 24 September 2021If 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.