When can action cards be played during a showdown? Can you respond to an opponent's action card with your own action card, or only when the chain is empty?

Ruling: Action cards can only be played during showdowns when you have focus and nothing is on the chain. You cannot respond to an opponent's action card with your own action card because once something is on the chain, you can no longer play action cards.

Nuances:

• On your turn when nothing is happening, you can play actions, reactions, or other card types freely
• Outside your turn or when things are happening, actions are restricted to showdowns with focus and an empty chain