Refract

Exile target creature you control and put a
shattered counter on it. If you do, create X 2/1
white and blue fragment creature tokens, where
X is that creature's toughness. They have "When
you own no creature cards in exile with shattered
counters on them, exile this creature" and
"Whenever this creature attacks and isn't
blocked, you may exile it and put a creature card
you own in exile with a shattered counter on it
onto the battlefield tapped and attacking."