Fated Finality

As an additional cost to cast this spell, sacrifice a
creature.
Draw X cards, where X is the sacrificed
creature's toughness.
Target player loses life equal to the sacrificed
creature's power if {b} was spent to cast this spell.
You gain life equal to the sacrificed creature's
power if {g} was spent to cast this spell. (Do both
if {b}{g} was spent.)