Ok after heavy experimentation Lord Siler and Blake came up with this unit called the "Spectral Knight"
From the early campaign files here are the stats:
1250hp
1hp/sec hp regeneration
No mana
First attack was a melee chaos type attack which did 50+ damage
Second attack was a ranged chaos type attack against air units also did more damage but had a longer cooldown
Heavy type armor, 9 armor
What made the unit really great were the abilities though:
Resistant skin
Spell Immunity
"Disempowerment Aura"
This third ability was a modified command aura which reduced all nearby enemies attacks by 30% - I think this was a stroke of genius, I mean this ability gives a tremendous advantage to any unit that has it.
The units were tremendously effective, although one disadvantage that was overlooked was that chaos type attacks do 100% damage against air units, while a piercing attacks do 200%, so the anti-air attack wasn't the best out there, but there you go.
A few of these would've destroyed your entire army, but they were rarely used, and when they were it was for defensive purposes, rather than attacking.