Shadowcutter

It is a very good idea and could also be implemented into PvP to help the balance there - like a separate PvP Build tree which would allow both PvP and NPC builds in the one toon.

After sleeping on it I also thought of things like..

enough points in "Buff/CM" pool to make CM an aura
or to turn 1 melee attack into a cone or PBAoE or whatever.

You get my drift.