Mysticism is the "you wear only cloth" bonus that all priests get at level 50. Unlike certain other classes, you don't really have a choice in getting this bonus. All specs get it.
Disc will AoE heal thorugh Holy Nova.
To get there, I expect Holy Nova to be radically reworked.
- First of all, they need it to heal for more than 2 digits worth of damage per cast.
- Second, The name is wrong.
- Third, as this is the only AoE heal for a disc priest, it will either need a range increase, OR be targettable somehow.
Of course, the latter option would put it right up the alley of the new paladin AoE heal, and reinstate all the Circle of Healing with no cooldown issues. So I'm not really sure what will happen, but it will probably work itself out somehow. I expect they will keep the spammable part though. It's not really Holy Nova unless it is spammable like crazy
No doubt, disc will be stronger at Single target healing than AoE healing. But you can't take the ability to AoE heal completely away from a disc priest. Unlike today, Holy Nova will have to be worth casting in MoP. We'll jsut have to wait and see how.