Permanents with "spiritcraft" have abilities that trigger "whenever you play a Spirit or Arcane spell." Since nearly every nonland card in the "Spiritcraft" deck is either a Spirit or an Arcane spell, nearly every spell you play has the potential to generate two, three, or even more bonus effects for free! With all these crazy abilities at your disposal, a properly timed Arcane spell can send your opponent's head—and creatures—spinning.