Can you play Action cards (like Block) during a Showdown on your opponent's turn?

Ruling: Yes, Action cards can be played during Showdowns on anyone's turn if you have focus. Action cards explicitly grant permission to be played during Showdowns even when it is not your turn.

Nuances:

• A showdown will always allow all players to play an action if they wish
• The cards themselves state "play on your turn OR IN SHOWDOWNS"