Players must ensure that double-faced cards in hidden zones are indistinguishable from other cards in the same zone. To do this, the owner of a double-faced card may use completely opaque card sleeves and/or a substitute card (see rule 713). Sanctioned tournaments have additional rules for playing with double-faced cards. See rule 100.6.
November 18, 2022 · The Brothers’ War
If a transforming double-faced card is cast as a spell, it’s put on the stack with its front face up by default. If a transforming double-faced card is cast “transformed” or “converted,” it’s put on the stack with its back face up. A player casting a modal double-faced card as a spell chooses which face they are casting before putting it onto the stack. See rule 601, “Casting Spells.”
September 24, 2021 · Innistrad: Midnight Hunt
If a transforming double-faced card is cast as a spell, it’s put on the stack with its front face up by default. If a transforming double-faced card is cast “transformed,” it’s put on the stack with its back face up. A player casting a modal double-faced card as a spell chooses which face they are casting before putting it onto the stack. See rule 601, “Casting Spells.”
July 23, 2021 · Adventures in the Forgotten Realms
If a transforming double-faced card is cast as a spell, it’s put on the stack with its front face up. A player casting a modal double-faced card as a spell chooses which face they are casting before putting it onto the stack. See rule 601, “Casting Spells.”
May 3, 2019 · War of the Spark
If a meld card is cast as a spell, it’s put on the stack with its front face up. See rule 601, “Casting Spells.”
January 25, 2019 · Ravnica Allegiance
If a meld card is cast as a spell, it's put on the stack with its front face up. See rule 601, "Casting Spells."
July 22, 2016 · Eldritch Moon
If a meld card is cast as a spell, it’s put on the stack with its front face up. See rule 601, “Casting Spells.”
September 30, 2011 · Innistrad
The effect that gives control of a player to another player may restrict the actions the controlled player is allowed to take or specify actions that the controlled player must take.