Rule 712.11 · Double-Faced Cards
A double-faced spell is cast with its front face up by default. See rule 601, “Casting Spells.”
Subrules
If a double-faced card or a copy of a double-faced card is cast as a spell “transformed” or “converted,” it’s put on the stack with its back face up.
A player casting a modal double-faced card or a copy of a modal double-faced card as a spell chooses which face they are casting before putting it onto the stack.
Only the face that will be face up on the stack is evaluated to determine if it can be cast. Only that face is considered to be put onto the stack.