NHF – new heroes for Heroes V 3.1.

Could you please provide more details about this concept?

Well, there's a storyline on one map about a character named Sar-something, who is the son of a human and an elf, studied magic, was friends with Dark Elves and necromancers, studied demonology, and then died, and everyone declared themselves his heir. You could create a character based on this story, and use this backstory to explain why he travels with a diverse army.