Btw theres a thing called wild magic in D&D which could be quite fun. Its basically a list of random effects that you roll a dice for which one activates. Certain types of mages get a chanche of this happening when they cast a spell or when some mage just messes up a spell. Or maybe you activate it on purpose. This is the biggest list currently http://www.traykon.com/pdf/The_Net_Libram_of_Random_Magical_Effects.pdf but its easy to find other ones or make your own.