Depending on the Deck Format you've chosen, we'll let you know as you build if your deck is in Legal status or not.
Depending on which rotation a format is in, certain cards may fall out of rotation, meaning they are no longer legal for a given format.
We'll highlight any cards that are no longer legal during deck editing.
If your deck is displaying Not Legal for your selected format, you can click on the orange Not Legal information text to view why your deck isn't in legal status.