Crow's Metamorphic Rite

As an additional cost to cast this spell, sacrifice a
creature. X is the Creature Converted mana cost.
Chose one:
- Create X 1/1 black Crow tokens, with Flying
and the Bird type.
-Add X+1 mana of any one color. Use this only
to cast creature spells.
"One thing can become another, or many others"