Phenomenon is a card type used with the Planechase variant. Phenomenon cards don’t go in a normal deck and aren’t cast from your hand. Instead, they live in a planar deck alongside plane cards. When a player planeswalks, the top card of the planar deck is revealed; if it’s a Phenomenon, its triggered ability resolves, representing a strange event or condition encountered between planes.
After that ability finishes resolving, the Phenomenon is put on the bottom of the planar deck, and the player planeswalks again to find the next plane. In a planar deck, Phenomena add unpredictability: they interrupt the usual rotation of planes with one-shot global effects that can alter life totals, libraries, permanents, or the rules of the game.
