NHF – new heroes for Heroes V 3.1.

The advantage of this hero will be significant, but the disadvantage is that he is only available for one Faction, and players who enjoy playing as other Factions will want this hero to be available in their Faction as well. This means that either such heroes should be included in all Factions, or they shouldn't be created at all.

Personally, I am against any conversions. In the case of the Necromancer, it's still somewhat acceptable, since there is already a troop conversion mechanic. And from the perspective of the game's lore, any city can be plagued and turned into a city of the dead. But for other Factions, there are no logical or gameplay justifications. Turning an Inferno into an Elven city? It's funny, yes. If such nonsense is allowed in a fantasy world, then it is clearly easier to build a city from scratch, i.e., in an empty location (rather than on the site of another city).

Added 5 minutes later

3) the hero should spend money on the conversion (at least 10,000 gold, and resources could be added as well).

Money for the plague? )))
What good would it do for a Necromancer to spend a lot of resources and then rebuild the city from scratch, when he already has a free creature conversion in his own city?