You have learned to cast spells using a different style than most of your spellcasting tradition.
Benefit: Choose one of the following ability scores – Intelligence, Wisdom or Charisma. All you spellcasting calculations are now based on this ability, including maximum level of spell you can cast, spell save DCs, and bonus spells per day. If you have spellcasting abilities from multiple sources, you can change all of them to this same attribute. Once this feat is taken and your new spellcasting attribute is selected, it cannot be changed.
Adventurer’s Handbook: Genius Guide Volume 1