The Wrong Wardrobe

As an additional cost to cast this spell, sacrifice
one blue creature with a converted mana cost of
three or more. Return exactly three black
creatures from any graveyard to the battlefield
under your control. If this enchantment is destroyed, all creatures it placed onto the battlefield are returned to their respective players' graveyards. (Even if those creatures are no longer
under your control.)
Well, it seemed like a good idea at the time!