Can the attacker activate a reaction card after both the attacker and defender have passed focus in combat?

Ruling: No, you cannot play a reaction after both players pass focus. Once both players pass focus in succession, combat moves to the damage step where no one has priority.

Sequence:

• Attacker passes focus
• Defender passes focus
• Combat resolves and moves to damage step (no priority available)

Nuances:

• If you pass focus and your opponent plays anything, focus comes back to you before combat resolves
• Both players must pass focus in a row for combat to resolve
• Reactions do not state "play at any time"