If a creature token is exiled this way, it will cease to exist and will not return to the battlefield.

Each card that returns to the battlefield will be a new object with no connection to the creature that was exiled. It won't be in combat or have any additional abilities it may have had when it was exiled. Any +1/+1 counters on it or Auras attached to it are removed, and any Equipment will no longer be attached.

If you choose two target creatures and one is an illegal target as Illusionist's Stratagem resolves, you'll exile the other, return it, and draw a card.

If each target creature is an illegal target as Illusionist's Stratagem resolves, the spell is countered. You won't draw a card.

You may cast Illusionist's Stratagem without any targets if you wish to just draw a card.