Hello everyone!
I like the version of (Heroes of Might and Magic IV: The Gathering Storm); I have many different builds for leveling up heroes. Mostly, I play as a Warrior paired with a Mage.
If we're talking about races, here's my approach:
CHAOS (Rogue):
First, Scouting.
Then, Combat.
Followed by Necromancy (resulting in a Vampire with the "Vampire Touch" effect).
After that, I try to focus on leveling up "Attack". (But usually, I don't get that far).
CHAOS (Sorcerer):
First, Chaos Magic.
Then, Nature Magic.
And if I have time, I'll go for Order Magic.

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NATURE (Ranger):
Combat.
Attack (from Tactics).
Life Magic.

NATURE (Beast Master):
I simply create a Beast Master (Nature + Combat).
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DEATH (Necromancer):
Death.
Life.
(The "Black Priest" effect)!?
DEATH (Knight):
Tactics (but I don't level up everything).
Combat.
Scouting (ONLY Scouting + Exploration).

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LIFE (Cleric):
Life.
Death.
(The "Black Priest" effect)!?
LIFE (Knight):
Tactics (but I don't level up everything).
Combat.
Scouting (ONLY Scouting + Exploration).
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ORDER (Mage):
Order Magic.
Nature Magic = Chaos Magic.
Chaos Magic = Nature Magic.
ORDER (Lord):
I level up skills related to money, etc.
And then I buy a Ranger (Nature).

These are my builds... but I don't always follow them, and it doesn't always work out as planned. Sometimes, the game doesn't allow me to do what I want, so you need to pay attention to the hero's destiny when you buy them; that way, it will be easier to achieve the desired effect....
In general, I've seen many different builds, and with them, many different effects that heroes can achieve....

Sincerely, AndersonAD