Red names in my deck?

[Palid]

Why are some of the cards name in my deck have a red name?

[Wally]

They are not legal cards in the format you are building for.

[Palid]

What makes them not legal there in the same block that I'm playing

[Gorzo]

What cards are showing up as red, and what format is your deck?

If they are Dragon's Maze cards, they will remain illegal until the set is officially released on Friday, May 3rd. Most formats also have a banned card list, which you may be using cards from.