Can actions be played in the middle of a chain, or only reactions? How does the pass/play priority system work when resolving chains?

Ruling: Actions can only BEGIN a chain, not be played in the middle of one. Once a chain exists, only reactions can be added to it. Both actions and reactions can be played when you have focus during a showdown (attacker first, defender second).

Sequence:

• An action or reaction is played, beginning a chain
• Players alternate adding reactions to the chain when they have priority
• When both players pass consecutively, the top effect on the chain resolves
• After an effect resolves, players again have the opportunity to add reactions before the next effect resolves
• This continues until all effects on the chain have resolved

Nuances:

• The chain does not resolve all at once when both players pass - only the top effect resolves, then priority passes again before the next effect resolves
• This is similar to Magic: The Gathering's stack system, not like Yu-Gi-Oh where the entire chain resolves at once