Still, 3 lizards are too many. Maybe it would be better to remove the lizard warriors and replace them with snakes (or something else)? Having lizards on three levels in a row is also quite absurd :(
Even the "Humans" have a peasant that is drastically different from a swordsman, who is not like a knight or a monk. In the case of lizards, this won't work because the archer and warrior are already too visually similar, and a caster (if they give him the same head) will completely ruin everything =/
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Maybe we could add swamp snakes to the lizard faction. We could base the snakes on water elementals.
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Well, wyverns were planned for the Orcs.
Rust dragons... IMHO, this is associated with some kind of mechanism, not with a spirit/giant lizard.