P.S. Zubr, don't be mad, I'm just grumpy in the morning.
Now, let's get to the point.
First up is Uvodd (yes, I made a typo:o (I can add an "d")).
1) The hero is designed as a powerful attacking mage with a set of spells for destroying single targets. I also added magical shackles, although I'm not sure why.
2) Death and Order magic have been added for the archmage class. I chose these schools of magic specifically because they have attacking spells. Of course, Death also has life drain at level 2, but firstly, it affects multiple targets, and secondly, it deals 66 damage. Considering that half of that damage will be absorbed by the mage, Uvodd can quickly build up a huge amount of health and become virtually unkillable, while also destroying all single-unit support units. Yes, this will only work against Life and Nature, but it will be enough.
3) As I mentioned, the set of spells is designed for single targets, so at level 4, he only has Choke. At one point, I considered adding Chaos magic level 5 with Disintegrate, but that would be an imbalance (if Choke deals 756 damage, how much would Disintegrate deal?).
4) I gave him the Aura of Dread to make it more difficult to block line of sight for subsequent spells.
5) The cloak is for increased army survivability and additional protection against Order magic.
Now about Erika Shadow.
I needed a fire mage class, which is why I chose Scout. I didn't give her Warfare because Erika has a large retinue, although, in reality, 1-2 levels of Warfare wouldn't be very useful.
Erika is, in some ways, the opposite of Uvodd. Her arsenal mostly consists of spells that affect an area on the battlefield and fire spells (fireball, fire ring, Inferno...).
1) Armageddon was given because it also affects an area. By the way, you underestimate it. When we played against each other with the Wanderer, this spell saved him a couple of times because it can't be blocked, unlike Fireball or Inferno.
2) Erika has a Dragon Shield, which reduces fire damage. Goblins-knights are almost immune to it anyway, with their innate resistance. But, by the way, the shield won't work with Armageddon, because Armageddon, unfortunately, is not a fire spell, but the shield will help against phoenixes, fire elementals, and there are a couple more things.
As for Jeddite. First, he is a tactician, and therefore the creature stats are quite impressive. Second, there are nightmares that can terrorize important/strong enemy units, adding the ability for the pyromancer's strike force to get within melee range.
When the enemy has overall bad luck and a hydra with Cat's Reflexes approaches his units, you can surrender immediately, because it will destroy everything. And by the way, nightmares also have a fairly large offensive potential.
Various troglodytes, minotaurs, and trolls can be used as you like, either as a tactic to cover and protect, or to absorb enemy attacks, or simply to support the strike force.
So, LeSHiJ-MaX, I tried to make each hero unique, rather than cramming all the power of a specific race into him. That's why the heroes' skills, their magical and combat arsenal are so different :)

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!