Spirit-Based Mana Regeneration: This system has been adjusted so that as your intellect rises, you will regenerate more mana per point of spirit.
This is no joke right now on the ptr. I went over there with 229 unbuffed mp5 while casting. On the ptr it bumped me to 266 mp5 unbuffed while casting. Seems this will allow for the drop of some mp5 gear/gems for haste gear.