When does Assault apply in relation to Ahri Legend's ability that reduces attacking units' Might by 1?

Ruling: Assault is a passive ability that applies as soon as a unit gains the attacker designation. By the time Ahri Nine-Tailed Fox's ability goes on the chain, the unit already has the attacker designation and thus already has the Assault bonus.

Sequence:

• Unit moves to battlefield and gains attacker designation
• Assault bonus applies immediately
• Ahri's ability triggers and goes on the chain
• Ahri's ability resolves, reducing Might by 1

Nuances:

• If Cleave is played after Ahri's trigger resolves (using the first focus of combat), a unit with base 3 Might will be at 4 Might (3 base + 3 Assault - 1 Ahri + 1 Cleave)
• If Cleave is played before moving the unit to battlefield to begin combat, the unit will be at 3 Might (4 base from Cleave + 3 Assault - 1 Ahri - 3 from Assault wearing off after Cleave resolves pre-combat)