Historical Rules · 5 February 2021
Rule 711.11
Official source text from the 5 February 2021 Rules release
If an effect allows a player to cast a double-faced card as a face-down creature spell, or if a double-faced card enters the battlefield face down, it will have the characteristics given to it by the rule or effect that caused it to be face down. That card remains hidden, using a face-down substitute card (see rule 713) and/or opaque sleeves. See rule 707, “Face-Down Spells and Permanents.”