When a player moves a unit into an empty battlefield and the opponent responds by moving a unit there (e.g., with Ride the Wind) during the conquer attempt, who is the attacker and who is the defender?

Ruling: The turn player who initially moved into the empty battlefield is the attacker, and the opponent who responded is the defender.

Sequence:

• Turn player moves unit into empty battlefield, attempting to conquer
• Opponent plays action card (like Ride the Wind) to move their unit into the same battlefield during the conquer attempt
• The battlefield becomes contested
• The player who applied Contested status first (the turn player) is the attacker
• The opponent is the defender

Nuances:

• If a unit with a "when attacking" trigger (like Yasuo) is moved in via Ride the Wind as the defender, that trigger does not activate since the unit is defending, not attacking