Can you play action cards (not just reactions) on your opponent's turn during combat?

Ruling: Yes, you can play action cards during combat on your opponent's turn when you have focus. Actions can only be played when you have focus and all triggers have resolved, while reactions can be played in response to actions or reactions.

Sequence:

• When showdown starts, an initial chain begins with "While I'm an attacker" and "While I'm a defender" effects where only reactions can be used
• After initial chain resolves, the attacking player gains focus and can play an action or reaction to start a chain
• Other players can only respond with reactions to that chain
• Once that chain resolves, the defending player gains focus and can play an action or reaction to start a chain
• Other players can only respond with reactions to that chain
• Focus passes between players until both players pass
• Each player can play multiple actions during combat when they have focus

Nuances:

• Actions can only be played by the player with focus when starting a new chain
• Reactions can be played by either player in response to actions or reactions
• Some cards like Super Mega Death Rocket are spells (not actions or reactions) and must be cast before/after combat only on your own turn