If an opponent's unit attacks a battlefield controlled by Ahri, gets -1 Might from her ability, then is bounced to base by Janna and re-enters the same combat via Ride the Wind, does Ahri's ability trigger again for -2 total?

Ruling: No, Ahri's ability will not trigger a second time. The unit will only have -1 Might total. Attack triggers can only be fulfilled once per combat per unit, even if that unit leaves and re-enters the battlefield during the same combat.

Sequence:

• Enemy unit attacks the battlefield, gaining the Attacker designation
• Ahri's ability triggers and resolves, giving the unit -1 Might
• Janna bounces the unit to base, removing the Attacker designation
• Ride the Wind moves the unit back to the battlefield
• The unit gains the Attacker designation again, but Ahri's ability does not trigger because it already fulfilled once for this unit during this combat

Nuances:

• This restriction applies because the same Showdown/combat is still ongoing. If the combat ended and a new combat was initiated at that battlefield later in the turn, Ahri would be able to trigger again for that new combat.
• Abilities that trigger when a unit gains the Attacker designation are classified as Attack Triggers and are limited to once per combat per unit, regardless of how many times they gain and lose the Attacker designation.