I thought about it, and if I were to just use the bare minimum Evocations points, I would probably spec for Bubble. There's not enough AAs available to us to get Stoneskins without sacrificing points from Conjurations tree (and I'm a real big fan of Enhance Plane Shift). However such a spec would require 40% worn spell haste, and such a setup is not likely to happen.
Bare Minimum Evocations + Bubble
With 4 points in Evocations (20% spell haste), there aren't enough leftover points to do anything really useful with. Maybe you could put 5 in Winds of Velious if you wanted, but if you toggle it like I do those points are wasted.
4 in Evocations + 8 Leftover