After moving into an occupied battlefield where both players pass without playing reactions, can the attacker play an action card?

Ruling: Yes, if there are no attack or defend triggers on the chain, you go straight to the showdown where the attacker gets focus and can play actions or reactions.

Sequence:

• Both players pass without playing reactions
• If there are attack or defend triggers on the chain, resolve those first (with both players passing in succession for each)
• If there are no attack or defend triggers, go straight to showdown
• Attacker gets focus and can play actions or reactions