Nesha, Queen of the Damned

Indestructible
As an additional cost to cast this spell, you may sacrifice any number of creatures. This spell cost {2} less to cast for each creature sacrificed this way.
When Nesha, Queen of the Damned enters the battlefield, create X 1/1 Black Zombie Creature
Tokens, where X is equal to the combined power
of all creatures sacrificed for the casting cost of
this card.