zombie (50)
zombie + zombie = vampire (150)
zombie + vampire = wolf (300)
vampire + vampire = succubus (400)
wolf + vampire = harpy (500)
wolf + wolf = nymph (650)
nymph + nymph = dragon (1200)
Succubus + Succubus = Yuki Ona (1000)
Succubus + Dragon = Lich (1800)
Yuki Ona + Harpy = Angel (1800)
Lich + Angel =?= Ultimate Girlfriend (???)