Double-faced cards
Core concepts
Transforming vs. modal DFCs — which face counts where, including in Commander.
How it works
There are two families. Transforming DFCs (Delver of Secrets, werewolves, the Ixalan flip-lands) enter front face up and flip to the back when something tells them to transform. Modal DFCs (Esika, the Kaldheim gods, the Zendikar Rising spell-lands) never transform: you choose a face as you cast or play the card, and it stays that way.
Outside the stack and battlefield, a DFC has only its FRONT face's characteristics. In your library, hand or graveyard it is whatever the front says, regardless of the back.
Common confusions
“Color identity in Commander.”
Both faces count, combined: every mana symbol in either face's cost and rules text, plus any color indicator. A card with a red back face can't go in a deck without red, even if its front is green.
“Mana value of a DFC.”
A transforming DFC always has its front face's mana value, whichever side is up. An MDFC uses whichever face is up on the stack or battlefield and the front face everywhere else — so a spell-land in your library has the spell's mana value, and is 0 once played as a land.
“Can I fetch an MDFC whose BACK is a land?”
No. In your library it has only its front face's characteristics, so "search for a land card" can't find it if the front face is a spell.
“Reanimating or flickering a DFC.”
An effect that puts a DFC onto the battlefield puts it front face up. If the front face can't be put onto the battlefield, the card doesn't enter at all.
“Can I play it as a land with a "cast" effect?”
No. An effect that lets you CAST a card doesn't let you play its land face; one that lets you PLAY it does. And an instruction to transform an MDFC is simply ignored.
Transforming double-faced cards
Ranked by how often Commander decks actually play them.
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