Vanille, Cheerful l'Cie

In the Commander variant, a double-faced card's color identity is determined by the mana costs and mana symbols in the rules text of both faces combined. If either face has a color indicator or basic land type, those are also considered. For example, Cecil, Dark Knight's color identity is black and white, since its front face is black and its back face has a white color indicator.

A nonmodal double-faced card enters with its front face up by default, unless a spell or ability instructs you to put it onto the battlefield transformed or allows you to cast it transformed, in which case it enters with its back face up.

A player prompted to name a card may name the combined back face, and each player has the right to know that combined back face's characteristics at all times.

Only two cards belonging to the same meld pair can be melded. Tokens, cards that aren't meld cards, or meld cards that don't form a meld pair can't be melded. If an effect instructs a player to meld cards that can't be melded, those cards remain in exile.

While a meld card is in any zone other than the battlefield, it has only the characteristics of its front face. The same is true while it's on the battlefield with its front face up.

When two cards are exiled and melded, they each leave the battlefield, then return together as one new untapped object with no relation to either of the objects that left the battlefield. Counters, Auras, Equipment, and other effects that affected those two cards don't affect the melded permanent.