mage aint for you go DD

if it has a MP pool and a Cure spell your a WHM no way around it

In regards to mana costs....unless I'm not understanding correctly, the ability to cast in passive will allow you to regen mana during battle. (This is where you chime in and say 'who wants to stay in passive and watch combat' and me being a positive as a hookers pregnancy test says 'Roll an active class')
defeats the purpose