Sidisi's Will

Casualty 3 (As you cast this spell, you may sacrifice
a creature with power 3 or greater. When you do, copy
this spell. The copy becomes a token.)
When Sidisi's Will enters the battlefield, destroy
target creature with mana value 4 or less.
Whenever you sacrifice a nontoken creature, you
may sacrifice Sidisi's Will. If you do, return that
creature from your graveyard to your hand.