The Delayer

Whenever you would create a token, put a delayed counter on The Delayer.
Whenever an attacking creature you control isn't blocked, you may {1}{u/b}, remove a delayed
counter from The Delayer and return that
creature to your hand. If you do, create a blue
Ninja creature token that's tapped and attacking.
That creature's power and toughness is equal to
the power and toughness of the creature you
returned to your hand this way.