How do chains work in Riftbound, specifically regarding actions and reactions during showdowns?

Ruling: During a showdown, both players can use actions and reactions. Actions can only start a new chain, while reactions and triggers can be added to an existing chain. The chain resolves like a stack (last in, first out), and combat damage only happens when both players pass priority without starting a new chain.

Sequence:

• Attacker has priority first and can play an action to start a chain
• Defender can respond with reactions (not actions) to the chain
• Players alternate adding reactions to the chain until both pass
• Chain resolves from top to bottom (most recent first)
• After chain resolves, attacker has priority again to start a new chain
• If neither player starts a new chain, combat damage happens
• Players can play multiple reactions before passing priority

Nuances:

• Actions cannot be added to an existing chain - only reactions and triggers can be added once a chain starts
• If P1 plays an action, P2 must wait for it to resolve before playing their own action (which would start a new chain)
• Showdown and chain are two different concepts - there can be many chains started during a showdown
• Seals are reactions that cannot be reacted to, but they do not automatically close a chain