NHF – new heroes for Heroes V 3.1.

The "deadly strike" ability cannot be considered imbalanced unless you use a cheat in the form of constantly saving and reloading to manipulate the random number generator.

It's not really fair to simply eliminate half of any stack, regardless of its size, with only a 25% chance, without checking the ratio of parameters.
Give a small chance to a weak hero, divide it into several stacks, and you get a chance to at least halve the stack once: 44% for two stacks, 58% for three stacks, 68% for four stacks.
If the ability worked with a standard check, I wouldn't have any complaints about it. :)

But 4 units of tier 6, yes, that's an imbalance.

With the possibility of obtaining them in the very first days, huh.
In general, in the first week, you can get several tier 6 units through Necromancy. But for this, you need to "accumulate some corpses" to break through the necessary pits/djinns/wyverns/ancients.

I would only allow them to be raised after building a structure in the city, for example, the Temple of the Underworld (a requirement for building a building for the Undead).

I would rework the Knights' abilities according to the following logic:
Heavily armored cavalry with a decent shield, consisting of such terrible creatures that even Necropolis couldn't find a place for them. :D

And as for Veres himself, here's roughly what a revision of his specialization might look like (a couple of options off the top of my head):