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For the Necropolis faction, you could try this setup for the third tier (using NHF models):
1. Bone Mages
2. Mummies
3. Banshee Ghost (easily modified from a Kikimora)
4. Nazgûl (several options to choose from, re-textured Spellcasters, Animists, etc., with the addition of the Vampirism spell)
5. Necromongers (a Necromancer model riding a Nightmare, in a Necropolis style)
6. Black Knights
7. Rotting Lamassu (black Manticores). Add poison and animal venom, and the Fear attack. Place Spectral Dragons in the first tier, renaming them to Bone Dragons (they don't really fit as ghosts), with the Death Gaze ability. Place Astral Dragons in the second tier, renaming them to Spectral Dragons, with the Etherealness and Horrific Presence abilities.
That's how I did it. It required some work in Photoshop and changing some abilities to my liking. The result is pretty good.
For the Humans, using the same base, I did this:
1. Warriors (Spearmen)
2. Archers: Double Shot, Maneuver (instead of crossbowmen from the second tier, named Archers, and crossbowmen are named Crossbowmen. I think this is more correct).
3. Battle Masters (there are several excellent models under different names; I liked Zealots more, or you could use a female model).
4. Garuda (instead of Royal Griffons, give regular Griffons the abilities of Royal Griffons).
5. I replaced the Inquisitors with the ones from the beta. They were removed for no reason; they look better.
6. Celestial Knights (Paladins on white dragons). This will require some work, either by requesting a separate model or, like me, re-texturing the Dark Champion (and consequently the Black Knight) to look like a Paladin and the black dragon to look like a white dragon (correspondingly, the neutral and Dark Elf factions have similar models replaced, and they are available in the mega-pack).
7. Move the White Angel to the first tier, and place the Cherub in the second tier (Resurrection, Blessing, Holy Word).
For the Elves:
1. Forest Spirits (there are some cool models in the form of lights; just change the voiceover, as they sound very unpleasant). Move alternatives 2 and 3 to positions 1 and 2.
2. Elf with a spear (you'll have to work with the model to add a shield, and you'll get a good balance with the Blade Dancers: +attack, -defense against -attack, +defense).
3. Forest Archers in green, with a cloak, and the Retaliation ability.
4. I divided the Druids based on their abilities (Hive Summoning, Stone Spikes vs. Lightning and Thunderstorm).
5. Pegasi. And give the Battle Unicorns the ability to strike once with lightning (like Erls). It's better not to find a new animation. If there isn't one, it stretches out, points its horn forward, and fires. I think this looks even more natural.
6. I removed the bald Ents, moved both alternatives to the left, and placed Ancient Ents (Dendroid Spellcasters) in the third tier.
7. I removed the Dragons completely, replacing them with Young Phoenixes (Firebird), Phoenixes, and Thunderbirds (+regeneration). If it seems that they give too much of an advantage to the pointy-eared faction, you can reduce their defense and attack, or add a +1 bonus to all three alternatives per week.
All these models are functional. You may need to work with the textures in some cases and give them new abilities as desired.
Yes, to avoid duplicates, the replaced models should be moved to the neutral faction.