Castle 1. For Spearmen and Halberdiers, the only suitable animation could be the animation of Dark Gnomes from the Rampart; therefore, they would need to be made taller and slimmer. 2. Arbalests already exist; one could perhaps create an arbalest unit that would be like the unupgraded version from the third game, without armor. In other words, an analogue of an archer but with an arbalest and a slightly different set of skills and stats. 3. Griffons exist; I haven't been able to figure out how to make them stand upright because the only flying creature that stands on two legs is the Wyvern. 4. There are already enough Swordsmen and their analogues. 5. Monks exist; I also haven't figured out how to create an analogue without a mace and crosses because I unfortunately noticed that none of the creatures in the game have an attack that is purely magical; they all have something physical – a weapon or bare hands. 6. Champions already exist in the original game. 7. Angels exist, but only as young ones; it would be nice to see some brutal, bearded ones as well. One could take an unupgraded angel, shorten its skirt, and make its color scheme resemble chainmail, put armor on its body, and change its hairstyle to a more masculine one, and of course, add a beard.

Added 2 hours 2 minutes ago
Rampart 1. Centaur Captains have already been implemented, so one could add regular ones by analogy and name them, for example, "Forest" Centaurs to distinguish them from the Orcish ones. 2. There are only Northern Gnomes in the game, so one could quite easily add "Forest" Gnomes, give them their hammers, and use the animation of either Warriors or Harpooners, whichever looks more appropriate. 3. Forest Elves exist in the game; one could add Noble Elves, similar to unupgraded Elves in armor. 4. It is difficult to implement models for Pegasus Riders because there are no flying horses or human/elf riders with swords in the game. The only option is to completely rework the Death Knight model and make Unicorns conditionally flying. 5. Good Ents already exist; there are no ideas yet on how to implement the Treants. 6. Unicorns exist. 7. Dragons exist.

Added 9 minutes ago
Tower 1. It's funny, but the only suitable option is Orcish Warriors with their flails on chains. For the animation of the shots, one could use the victory animation. 2. The only more or less suitable model for humanoid Gargoyles is the Demoness, but its implementation is hindered by, uhm, female sexual characteristics. 3. The only suitable option for "fist-fighting" Golems is Bone Golems/Berserkers; one just needs to remove the beard. 4. Mages with staves can only be created from Rune Priests, so one needs to somehow add height and slimness. 5. Vampire Princes have the exact same hairstyle as the Tier 3 Djinns; one could do as with Medusas and Nagas, attaching the bodies of the Vampire Princes to the "Whirlwind" Djinns. But this raises the question of animation because no one has an animation of attacking with magic. 6. Nagas have been implemented. 7. As far as I understand, it is possible to give Colossi a sword, but the question is, what attack animation will they use?