The Dark Elves were a pleasant surprise (surprisingly high-quality replacement for the Mage Guild city). However, I'm a bit concerned that everywhere you look, the entire city is filled with elves and elf-like creatures. The only exception is the mountain goats, which, of course, are ridden by... elves! (who would have thought). There are some faceless units, but they don't change the overall impression. All the units in the castle look too uniform; the original elves have a slightly more diverse army...
In this regard (to add some variety to the Dark Elves), I suggest replacing the 7th-level unit with stone, ice, or some other type of dragon. This would eliminate the monotony and uniformity of this race... just my opinion.
Also, as a "tester," I have a suggestion.
The Magic Chimeras don't fit with the main storyline of "Heroes." In general, magic chimeras are a separate order of mages, but on what basis did THIS order survive after the cataclysm? (I understand that it's too early to delve into the plot, but still). I had an alternative idea for a new race: a kind of "Pirate Brotherhood" (similar to "Asylum" from Heroes 3). Here, you could also create a good storyline right away. For example, you could say that after the cataclysm, many people found refuge in some archipelago...
The model of a pirate (and its upgrades) can be borrowed from the NCF mod. I think that such a faction would look very logical against the background of the future storyline... Moreover! The racial "ability" of the Elven cities, "Ranger Guild," can easily be renamed "Cutthroat Guild." The main thing is that it fits the meaning very well.
Thank you for your understanding.