If Cleave is played on a unit after it has already moved to a battlefield and been declared an attacker, does the unit still get the +3 Might from Assault?

Ruling: Yes, the unit gets +3 Might from Assault. Assault is a passive ability that applies as long as the unit has the attacker designation, regardless of when the unit gained the Assault ability.

Nuances:

• The timing of when the unit gains Assault does not matter
• The key requirement is that the unit has the attacker designation