If you follow his build Nae, you would need to use Adamantine Cloak for the +2 spell mastery or your build will not have any focus items. You would still lose the +3 evocation focus, +3 enchantment focus, and +3 necro focus in that build.
His solution to solve the +3 necro focus loss is to swap in "staff of the necromancer" when he needs it. It's okay for him to lose the 2 lobs in the meantime I guess. You would still be losing +3 evo & +3 enchantment bonus unnecessarily.
With the current build, you don't need Epic ring of the mire. You can use the 2/day stone skin clickie for 10/adamantine (Min II), keep a stone skin spell in your hotbar, or simply have the Mabar's night cloak that gives DR 10/good. Both 10 DRs are better than greater spear block. (Remember,
DRs do not stack , 10/good & 10/ada will overtake 10/slashing greater spear block).
From what I see, Major stats you're throwing away are 1 dc from evocation, enchantment, and necromancy; losing boon of undeath; and losing max nullification +114; for a +1 profane int litany.