If my opponent moves a unit to an empty battlefield and I respond by playing Ride the Wind to move my unit to that same battlefield, does combat occur and who is the attacker/defender?

Ruling: Yes, combat occurs. Your opponent's unit is the Attacker and your unit is the Defender because their unit applied contested status to the battlefield first.

Sequence:

• Opponent's unit moves to empty battlefield and applies contested status, starting a non-combat showdown
• You play Ride the Wind, moving your unit to that battlefield
• Combat is now staged because units from two players are present
• The non-combat showdown resolves normally
• The staged combat showdown begins with your opponent as Attacker