Gladiaxa
The officer who had reached out to the orbiting ship laughs.
"Who said we need to take the whole base? We are the servants of the Circled Star, and we bring the light of terror to all its enemies. And as for you..." He squeezes, a satisfied smile on his face as the rebel chokes and scrabbles at his hand, trying desperately to get some air.
"We'll get what we want, one way or another."
Then the teleport flares up again and the party from the ship and the troopers are gone. Seconds later, MAC rounds scream down from the heavens and turn the rebel base into a crater. Above, the ship maneuvers until its railgun is aimed at the planet and then it pulses. On the surface, a streak of fire slams into the already shattered ground. Only this time, a noxious black goo seeps out of the gaping wound in the earth... Then the ship jumps to FTL with its prisoners aboard.
Over the following weeks and months, the goo will steadily eat its way into the planet, infecting everyone who comes into contact with it. Indeed, after several weeks, the mass is capable of independent thought. Two weeks after that, it can manifest short-lived avatars to attack any local resistance. The Old Imperium never gave a name to this type of genocidal weapon, but that makes it no less of an abomination...or deadly.