Byode, Inverse Sun is a mythic Legendary Universewalker — Byode card from 2021 Heroes of the Realm (PH21), collector number 3.
+2: Mill three cards, then return any number of cards from different Universes milled this way from your graveyard to your hand. -X: Choose a Universe you haven't chosen this way this game. You may cast a spell from that Universe with mana value X or less from your hand without paying its mana cost. Byode, Inverse Sun can be your commander. Your deck can include Universes Beyond cards of any color identity.