Historical Rules · 16 January 2016
Rule 711.3b
Official source text from the 16 January 2016 Rules release
If a checklist card is used in a deck, the double-faced card it represents is set aside prior to the beginning of the game (see rule 103.1a) and must remain available throughout the game. A checklist card can’t be included in a deck unless it is representing a double-faced card.