How do actions and reactions work during a showdown in Riftbound, particularly regarding turn order and when each can be played?

Ruling: Actions can only be played when there is no chain (when you have focus). Once a chain starts with either an action or reaction, only reactions can be played until the entire chain resolves and focus passes to the next player.

Sequence:

• Player with focus can play an action or reaction to start a chain
• Once a chain exists, both players can only play reactions (passing priority back and forth)
• When both players pass priority in order, the top link of the chain resolves
• Priority passes again and players can add more reactions or pass
• Once the full chain resolves, focus passes to the next player
• The next player can then play an action or reaction to start their own chain
• When both players pass focus on an empty chain, the showdown ends

Nuances:

• Reactions can react to action spells, but action spells cannot be played in response to other actions once a chain has started