Ajani, Inspiring Leader

• WWizards of the Coast2019-07-12
  Official Ruling
  Ajani’s last ability affects only creatures you control at the time it resolves. Creatures you begin to control later in the turn won’t gain flying or double strike.
• WWizards of the Coast2019-07-12
  Official Ruling
  If the target creature is an illegal target by the time Ajani’s second ability tries to resolve, the ability doesn’t resolve. No player will gain life.
• WWizards of the Coast2019-07-12
  Official Ruling
  You may activate Ajani’s first ability without choosing any target. If you do, you will gain 2 life. However, if you do choose a target and the target creature is an illegal target by the time the ability tries to resolve, the ability doesn’t resolve. You won’t gain 2 life.

Rulings via Scryfall