If I use Ride the Wind to move Yasuo Remorseful into a battlefield where I'm already attacking with another unit, does Yasuo's When I Attack ability trigger?

Ruling: Yes, Yasuo's When I Attack ability will trigger when he becomes designated as an attacker during the cleanup of his arrival.

Sequence:

• Attack a battlefield with a unit
• Use Ride the Wind to move Yasuo Remorseful into that battlefield
• Yasuo becomes designated as an attacker during cleanup of his arrival
• Yasuo's When I Attack ability triggers and starts its own chain