Ok ok ok, let me get this straight:
You just made up a spell, that absorbs mana to your own character. To cast this spell, it costs the player a certain amount of mana.
Ok...
So basically, you get mana for nothing. Yeah... great spell... woo! <img src="/ubbthreads/images/graemlins/silly.gif" alt="" />
I have the feeling you didn't quite think this through... <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />