Hall of Mirrors — ruling 1

Hall of Mirrors copies the printed values of the target creature. It won’t copy any counters or stickers on that creature or any effects that have changed its power, toughness, types, color, and so on, and a creature becoming a copy doesn’t remove any such counters or effects that are already applying to it. Notably, Hall of Mirrors won’t copy any type-changing effects that are currently making the target a creature. For example, if you choose a land that’s become a creature, all your other creatures will become noncreature lands until end of turn.

Hall of Mirrors — ruling 2

If the chosen creature is copying something else, other creatures you control become copies of whatever the chosen creature is copying.

Hall of Mirrors — ruling 3

If the target creature is a token, other creatures you control will copy the original characteristics of that token as stated by the effect that created the token. Any of those creatures that aren’t tokens won’t become tokens in this case. Similarly, if the target creature is a nontoken creature, creature tokens you control won’t stop being tokens.

Hall of Mirrors — ruling 4

Hall of Mirrors affects only creatures you control at the time its ability resolves. Creatures that come under your control later in the turn won’t be copies of the chosen creature.

Hall of Mirrors : règles, fonctionnement et interactions (MTG)

Hall of Mirrors 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

Visit — Choose target creature you control. Each other creature you control becomes a copy of that creature until end of turn, except it isn't legendary.

How it works : Hall of Mirrors

Original English text — Wizards of the Coast / Scryfall

#1October 7, 2022· Wizards of the Coast
Hall of Mirrors copies the printed values of the target creature. It won’t copy any counters or stickers on that creature or any effects that have changed its power, toughness, types, color, and so on, and a creature becoming a copy doesn’t remove any such counters or effects that are already applying to it. Notably, Hall of Mirrors won’t copy any type-changing effects that are currently making the target a creature. For example, if you choose a land that’s become a creature, all your other creatures will become noncreature lands until end of turn.
No other card is named in this ruling.
#2October 7, 2022· Wizards of the Coast
If the chosen creature is copying something else, other creatures you control become copies of whatever the chosen creature is copying.
No other card is named in this ruling.
#3October 7, 2022· Wizards of the Coast
If the target creature is a token, other creatures you control will copy the original characteristics of that token as stated by the effect that created the token. Any of those creatures that aren’t tokens won’t become tokens in this case. Similarly, if the target creature is a nontoken creature, creature tokens you control won’t stop being tokens.
No other card is named in this ruling.
#4October 7, 2022· Wizards of the Coast
Hall of Mirrors affects only creatures you control at the time its ability resolves. Creatures that come under your control later in the turn won’t be copies of the chosen creature.
No other card is named in this ruling.