When Noxian Runner moves from base to an empty battlefield, can the opponent play Hextech Ray before the 'When I move, Recruit a unit here' trigger resolves?

Ruling: No, the opponent cannot play Hextech Ray before the Recruit trigger resolves. Hextech Ray has the action keyword, so it can only be played in a neutral open state (nothing on the chain and the other player has passed focus), not while a trigger is on the chain.

Sequence:

• Noxian Runner moves to the battlefield
• The 'When I move, Recruit a unit here' trigger goes on the chain
• The trigger must resolve before Hextech Ray can be played
• After the trigger resolves and the showdown starts, the active player gets focus first
• Only after the active player passes or their action/reaction fully resolves can the opponent play Hextech Ray

Nuances:

• Actions can only be played in neutral open state (outside showdowns with nothing on chain)
• Even after the trigger resolves, the active player receives focus first before the opponent can act