During a Riftbound showdown, when can players play actions vs reactions, and how does priority/focus work during chain resolution?

Ruling: Actions can only be played when the chain is empty (to start a new chain). Reactions can be played at any time during a chain. When you have focus and priority, you can play action > reaction(s) and pass priority. After a chain resolves, focus and priority automatically pass to the opponent.

Sequence:

• Player with focus can play an action to start a chain
• That player retains priority and can add reactions to their own chain
• When they pass priority, opponent can add reactions
• Chain resolves one link at a time, starting from the top
• Player who owns the next resolving link gets priority first
• Both players must pass priority for each link to resolve
• When the last item resolves, focus and priority automatically pass to the opponent
• Opponent can now start a new chain with an action or reaction
• Showdown ends only when both players pass in succession while the chain is empty

Nuances:

• You can play reactions even during chain resolution (when drawing cards from resolving effects)
• When something resolves and you draw a card (like Defy from Discipline), you can play it before the next link resolves
• The player who owns the next link to resolve gets priority first, but both players get priority before it resolves
• Defy can target any valid spell in the chain, not just the last one played
• You cannot play actions in response to an existing chain - only reactions