not for combined, but, I made a level 3 fire spell ( or 5, I don't remember )
and I have only around 160 spell point, with the spell cost ( display around 100 mana cost ), I can logically cast only one, but, in fact, I can cast 3 of them <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />
Edit, take a look on my shot :
http://jilin.free.fr/div/manabug.jpgthe real mana cost looks to be half of the displaying one <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />