3.6 Chaos zombies - theory

Core idea : zombies with chaos damage.
Spirit offering + Withering touch + Unholy might -> 90% of physical damage as extra chaos damage.
Zombie + Melee physical dmg + Minion dmg + Withering touch + Void manip.

Stack it with Withering and Despair.

Possible augmentations :

Necro Aegis :
- Broken faith for Unholy might
OR
- Victario's Charity for charges
or something else


Umbilicus Immortalis :
- Atziri's Promise for damage
- Sin's Rebirth for Unholy might
- Witchfire Brew for Despair curse
- Coruscating Elixir for Boooom

Not sure about Mon'tregul's Grasp.
I don't want to go into Baron, but I believe Baron builds also can go chaos way.

I didn't play already for a very long time, so please advise : will zombie build benefit of chaos damage focus? Or classic zombie build is better?