5p74
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@5p74
Unfortunately, this won't happen. Dragons are the children of Malassa, who the dark elves worship. So, separating the dragons from the dark elves doesn't make sense according to the plot. Minotaurs are slaves of the dark elves. Slaves can revolt and free themselves. Hydras are creatures that the dark elves breed. Perhaps, simply abandoning the breeding of hydras is not possible. There needs to be some reason. So, if the developers follow the plot (and they will), then the dungeon will remain as it is.
But in the first parts of Heroes, there were no dark elves; hydras, minotaurs, and dragons lived separately (with the Sorceress) - it was in the 5th part that they were mixed together and a new story was created.
Added 15 minutes ago
@5p74
Now about the last point of your request. IMHO, 10 creatures is too many, but the main thing is difficult to implement. It is necessary to have 3 creatures for each castle, which would fit into the castle. If we talk about the 4th option, remember what it led to. There were some kind of zombie creatures that no one took into their army. However…
If you mean the 4th part, where units were offered to choose from, then I suggest that there be 5th-level creatures, 2 of each, and you can take all of them without choosing. 5th level is so that there are fewer low-level creatures, because in Heroes they are quickly defeated, and in the later stages of the game (mainly in 3 heroes) they were often replaced by 6th and 7th-level creatures from other castles.
And it's not that difficult to add 3 units to each castle.
I suggest the following options:
Empire: pikeman, squire, paladin
Elves: pegasus, satyr, phoenix
Undead: werewolf, undead knight, mummy
Demons: efreet, incubus, devil servant (anti-paladin)
Dwarves: yeti, flamethrower, valkyrie
Wizards: dragon golem, magic elemental, wizard
Sorceress: cyclops, manticore, some dark elf
Barbarians (horde): monster, thunderbird, ogre or troll