The Girl in the Fireplace — ruling 1

To time travel, look at each permanent you control with a time counter on it and each suspended card you own in exile with a time counter on it. For each of them, you choose whether you want to put a time counter on that card or permanent, remove a time counter from it, or do neither. Then those changes all happen simultaneously.

The Girl in the Fireplace — ruling 2

Time counters are usually found on cards with suspend and vanishing, but may be found on other cards as well. Notably, Sagas use lore counters to track their progress, not time counters. You can't move a Saga's chapters forward and backward this way.

The Girl in the Fireplace : règles, fonctionnement et interactions (MTG)

The Girl in the Fireplace 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

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Create a 1/1 white Human Noble creature token with vanishing 3 and "Prevent all damage that would be dealt to this token." II — Create a 2/2 white Horse creature token with "Doctors you control have horsemanship." (They can't be blocked except by creatures with horsemanship.) III — Whenever a creature you control deals combat damage to a player this turn, time travel.

How it works : The Girl in the Fireplace

Original English text — Wizards of the Coast / Scryfall

#1October 13, 2023· Wizards of the Coast
To time travel, look at each permanent you control with a time counter on it and each suspended card you own in exile with a time counter on it. For each of them, you choose whether you want to put a time counter on that card or permanent, remove a time counter from it, or do neither. Then those changes all happen simultaneously.
No other card is named in this ruling.
#2October 13, 2023· Wizards of the Coast
Time counters are usually found on cards with suspend and vanishing, but may be found on other cards as well. Notably, Sagas use lore counters to track their progress, not time counters. You can't move a Saga's chapters forward and backward this way.
No other card is named in this ruling.