If you insist to your idea of having Desolation and Wandering Plague (both unneeded by my opinion), at least don't steal yourself by talenting Imp. Icy Touch and spend those points in RoR, not the points from Black Ice. This way you'd have your (gimp) maximum AoE TPS build. Still unnecessary, but you'll find that out later, at wich point you will spend all those gimp points in quality of life points instead, arriving to the build I suggested in the first place. Have a nice journey tho.