Turtle-Duck

• WWizards of the Coast2025-10-02
  Official Ruling
  Effects that modify Turtle-Duck's power without setting it will apply no matter when they started to take effect. The same is true for counters that change its power.
• WWizards of the Coast2025-10-02
  Official Ruling
  Turtle-Duck's ability overwrites all previous effects that set its power to a specific value. Other effects that set its power to a specific value that start to apply after the ability resolves will overwrite that part of the effect.

Rulings via Scryfall