310. These descriptions can be combined, such that the turn is always in one of these four states:

310.1. Neutral Open: There is no Showdown in progress and no Chain exists.

310.1.a. By default, cards can be played and abilities activated only when a player has priority on their turn in a Neutral Open state.

310.2. Neutral Closed: There is no Showdown in progress and a Chain exists.

310.3. Showdown Open: A Showdown is in progress and no Chain exists.

310.4. Showdown Closed: A Showdown is in progress and a Chain exists.