If Yasuo deals damage to a unit when attacking, then is moved back to base before combat resolves, does the damaged unit heal or does the damage persist?

Ruling: Once Yasuo attacks and triggers combat, a combat cleanup will occur at the end of the showdown. During cleanup, units heal all damage unless they were killed.

Sequence:

• Yasuo attacks Battlefield A, triggering his ability and dealing 6 damage to a unit
• Yasuo is moved back to base via Ride the Wind
• Combat showdown completes
• Combat cleanup occurs, healing all surviving units

Nuances:

• If the 6 damage killed the unit (reduced it to 0 or less might), it remains dead
• If the unit survived the damage, it heals back to full during combat cleanup