Does Legend Ahri's trigger apply to creatures that enter the battlefield after a showdown has already begun (e.g., via Ride the Wind)?

Ruling: Yes, Legend Ahri triggers on units that gain the attacker designation after combat has begun.

Sequence:

• Combat begins and Ahri triggers on attacking units
• A unit joins the fight later (e.g., via Ride the Wind)
• Ahri triggers again on the newly arriving unit

Nuances:

• Ahri triggers whenever a unit gains the attacker designation for the first time at a battlefield her owner controls, regardless of when during combat this happens