Impostor Syndrome

• WWizards of the Coast2025-09-19
  Official Ruling
  If the copied creature is copying something else, then the token enters as whatever that creature copied, with the listed exceptions.
• WWizards of the Coast2025-09-19
  Official Ruling
  If something becomes a copy of the token, the copy also isn't legendary.
• WWizards of the Coast2025-09-19
  Official Ruling
  Any enters-the-battlefield abilities of the copied creature will trigger when the token enters the battlefield. Any "as [this creature] enters" or "[this creature] enters with" abilities of the creature will also work.
• WWizards of the Coast2025-09-19
  Official Ruling
  If the copied creature has in its mana cost, X is 0.
• WWizards of the Coast2025-09-19
  Official Ruling
  Except for not being legendary, the token copies exactly what was printed on the original creature and nothing else (unless that permanent is itself copying something else; see below). It doesn't copy whether that permanent is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.

Rulings via Scryfall