"And you were almost finished with that ritual, weren't you, darling? How very rude of me. To make it up to you, I'll send you an invitation to my wedding."

Olivia's Midnight Ambush

Target creature gets -2/-2 until end of turn. If it's night, that creature gets -13/-13 until end of turn instead.

Innistrad: Double Feature

Innistrad: Midnight Hunt

For more information about Day and Night and the Daybound and Nightbound abilities, please see the Innistrad: Midnight Hunt Mechanics atricle (https://magic.wizards.com/en/articles/archive/feature/innistrad-midnight-hunt-mechanics-2021-09-02).

The phrase "if it's night" refers to the day or night designation the game can have. It does not refer to whether or not it's dark outside as you play the game.