Historical Rules · 7 June 2024
Rule 718.3c
Official source text from the 7 June 2024 Rules release
If a prototyped spell is copied, the copy is also a prototyped spell. It has the alternative power, toughness, and mana cost characteristics of the spell and not the normal power, toughness, and mana cost characteristics of the card that represents the prototyped spell. Any rule or effect that refers to a prototyped spell refers to the copy as well.