Disclaimer : This is told from the antagonist's perspective
3,000 years ago, we sent a probe containing a new, recently discovered substance to a newly discovered planet to study its environment. Due to little results, the project was abandoned.
Now, 3,000 years later, a species calling themselves "humans" have occupied this planet as their home, fleeing their broken homeworld. They have discovered our substance, calling it "mithril" and applying it to their many militaries. They haven't even began to comprehend its full potential.
We want it back.
We've sent an advance team of sorts: millions of our own wildlife, genetically programmed to seek and destroy humans. The humans have largwly defeated them.
My war fleet is traveling at near lightspeed to the planet, which the humans have dubbed UBW-594244. We are bringing some new species with us, the likes of which the humans have never seen.
They've had their fun. Now it is time to show them what it truly means to be our enemy.