[@Nanashi Ninanai]
Madb already exists as a Rider though. We won't deny her, but it would be appreciated if you used a Servant that wasn't previously used in Type-Moon. Or if you manage to change her enough to create disparity with the TM version we will accept her. Changes on the level of Elizabeth Bathory into Carmilla or Dracula from Fate/Extra into his Appocripha version should be enough.