What types of cards can be played during showdown, both on your turn and when it's not your turn?

Ruling: During showdown, you can use both actions and reactions regardless of whose turn it is. For actions, the chain must be empty and you need Focus and priority (attacker has priority first, then defender).

Nuances:

• Spells with no action flag (base speed) can only be used on your turn, outside of showdown, when the chain is empty
• The same restriction applies to activated abilities unless they state otherwise