Can action spells be played during showdowns, and what are the timing restrictions?

Ruling: Action spells can be played during showdowns (including on your opponent's turn), but only when the chain is empty and you have focus. You cannot chain action spells to other abilities.

Sequence:

• When you gain focus during a showdown, you can play an action spell as the first link in a new chain
• If your opponent has focus, they must pass it to you without activating anything before you can play an action
• After an action spell resolves, the chain ends and focus passes around
• Reactions can be played in response to triggers, but actions require an empty chain

Nuances:

• The card text "play on your turn or in showdowns" allows actions during any showdown, even on opponent's turns
• The opponent with priority has the first chance to play an action spell
• After their action resolves and the chain is empty, you can then play an action spell in a new chain