I run 4 arcane mages and one Disc priest..... Holy Nova spamming on the same button your Arcane Explosion spams on = Sooooo easy.
Get the glyph that makes holy nova heal for 60% more but does less damage and its cake. Also having a priest fear bomb makes pulling more mobs easy.

If you have the time to try it.. i think you would like it. Reason priest is disc is for better stam and spirit/spell dmg buff. Holy wouldnt be a bad choice as your holy nova would heal better.