I've been watching the Miniwargaming videos and came across Primal Horizon. I have two faction ideas (yes I know about it):
Deathlings:
After the apocalyptic events, humanity seemed to forget about the dangers they had created that they had once used for benfiet. One of these, is nuclear power plants (yes, some sort of mutants are bound to come out of this

People had avoided these power plants knowing they were dangerous, but otherthing did not.
Deathlings are mutated wasps, that have spawned from the very exsistance of these power plant explosions. The radiation must have caught a hive, causing the survivors to mutate.
With these mutations, they have become powerful enough to overrun humanity, but still keep swarm instinct.
I think this could work with the gameplay. They would be around half the size of a normal character, but have greater numbers (not by too much, though). Range could be worked out by them launching their stingers or spraying acid.
Thoughts?