[Requesting Cover Image!] [A STO crossover]
"We are the Borg. Existence as you know it is over. We will add your biological and technological distinctiveness to our own. Resistance is Futile..."

The Borg, a Cybernetic life-form from the Delta Quadrant is a threat to all life in the Alpha Quadrant. The Federation and The Klingon are in a truce against this odd but dangerous enemy, eventually, The New Romulan Republic gave their best in the military to support the frontlines.

However, the Borg seems to give up, each assault become weak or reduced into lone scout parties of a single cube and few probes or spheres.
Starfleet suspect that the Collective has a new target. Capturing a sphere reveals that the borg has their eyes (or optics) in a planet with unusual radiation but no only that, the natives can BEND that radiation, transforming or change it from harmless amount of it into dangerous but controlable ones, Starfleet Suggest in defending the planet from the Borg but also in secret from the natives, because if its inhabitants fall into the hands of the Borg, the war against said menace can turn into a nightmare.

The Alliance of the three factions sent a fleet to the coordinates of said Borg sphere to create an outpost and defend the planet
...
Mainwhile in Equis, Equestria.

The Princesses, Celestia and Luna, have visions about aliens, fighting against abominables machine for the sake of equestria.
fearful about the visions, The Princesses found in the Ancient Archive about a prophecy... a prophecy of Star Soldiers and the Machine Hive.

"Heroes beyong the skies rise against the hive"
"Blue Explorers of the sea of stars brings logic against the odds"
"Red Warriors of Great Honor brings valor against the Horror"
"Green Soldiers of once Mighty Empire brings salvation against damnation"