...is the highest form of flattery.
"You elders like to use ranged combat but have terrible armor? Cool, we got an adaption for that!".
IMHO the Tyarnids of Warhmmer 40k are the scariest foe imaginable (on level of the Borg from Star Trek):
Because they combine the lack of value for life of a swarm.
With a adaptability that makes humans look creatively sterile in comparision.
And the mind of a great tactician with galactic ambitions.
But that's because I always hated the concept of biological (organic) superiority over manufactured. In RL, you'll never find anything even remotely like that. Metals and focused technology outperforms organic matter in many areas, most notably durability and stress tolerance.
Bone swords vs. power swords?
guns vs. acidic spit?
Armor vs. carpace?
Biology is just manufacturing on a nano scale, with some inherent self repair.
Our bones are not harder, because at our gravity we don't need them to be harder. They are not overengineered as the stuff we can manufacture.
But a species that mastered biotechnology could overengineer thier bodies.
Even the smalest nyd is highly overengienered compared to a Eldar or human. After all there is no need for any reproductive organs. "Can't reproduce" is a serious flaw for any lifeforms design, but can work if it is part of a swarm.