User blog comment:Beatnik Doctor/Solving the Energy Crisis/@comment-1990160-20110922105300

I believe that one of our editors has been inside the game files, and observed the base mana values of ninjas to be -10000. Therefore, any bonus mana would cause it to become like -9000. Apparently, Riven had a base mana of 0, which made her different from all other manaless champions.