Aerial Assault

• WWizards of the Coast2019-07-12
  Official Ruling
  If any creatures were exiled "until" the target creature left the battlefield, those creatures will return before you gain life.
• WWizards of the Coast2019-07-12
  Official Ruling
  Any abilities that trigger as the target creature is destroyed won't resolve until after you've gained life.
• WWizards of the Coast2019-07-12
  Official Ruling
  If the target creature is an illegal target by the time Aerial Assault tries to resolve, the spell doesn't resolve. You won't gain life. If the target is legal but is not destroyed (most likely because it has indestructible), you will gain life.

Rulings via Scryfall