After an action resolves on an empty chain during combat, who gets focus first? Specifically, if Kai'Sa Survivor is attacking and opponent's Hextech Ray resolves, can the attacker play Cleave before the opponent can play a second Ray?

Ruling: When the last card on a chain resolves, focus passes to the other player. After the first Hextech Ray resolves (making the chain empty), the attacking player gets focus first and can play Cleave before the opponent can play a second Ray.

Sequence:

• Kai'Sa Survivor attacks into empty battlefield
• Attacker passes focus
• Opponent plays Hextech Ray, it resolves
• Chain is now empty, focus passes back to attacker
• Attacker can now play Cleave before opponent can play second Ray

Nuances:

• If the attacker plays Cleave first and lets it resolve, focus then passes to the opponent, who can then play an action before the attacker can play another card
• You cannot play an action, let it resolve, then immediately play another action without giving your opponent the opportunity to respond
• Cleave wouldn't save Kai'Sa when moving into an empty battlefield since assault requires an active combat for the might gain to work