I didn't know either. After reading up about it I figured out the book should go red when the spell is too complicated. Something I didn't notice before blowing my altar.No one told me it would EXPLODE. What is this, Gregtech ?! Great. And of course, AFTER i used my materials ! Bah. I just wanted to make an complex spell to level up my magic, so i finally could get a red skillpoint for flying.