I own nothing but the Zenos and the human characters not shown in the movie.
Admiral Stark turned as one of the soldiers whispered to him. "Sir, I can see something!" he said. Stark looked through the small slits that the soldiers could fire through and saw several dark shapes in the fog. Suddenly one of the shapes lunged forward and he lurched back as a Zenos came into view. It banged its head against the wall and Stark loaded his gun, then fired through the hole. Blood spurted through and the creature whined, then dropped to the ground. "Open fire!" he yelled as more of the shapes appeared through the fog. The Zenos were small, about the size of an average puppy, but their skin was a much lighter red than the other zenos species he knew about.
"Sir! They're trying to break through the door!" one of the soldiers yelled. Admiral Stark turned to see one of the boards they'd blocked the door with break off from the weight being thrown on the door from the other side. Admiral Stark ordered his men to load the guns, then he called the order to stop shooting. All the soldiers stood at the ready as Rob stood beside Admiral Stark, holding a handgun and staring confidently at the door. A clang made all but the admiral flinch, and another one of the boards was split in half, falling to the ground. There was only one board left. Silence took them for a moment, then Admiral Stark felt his stomach clench as he heard the small skittering steps be replaced by much larger and heavier steps. It only took one hit this time to knock the board clean off, and moments later the door had four large dents in it. Several of the soldiers raised their guns, and Admiral Stark raised an eyebrow as the hits stopped. Then he heard the heavier steps pick up speed and he yelled, "Brace yourselves!!" as the door was hit by something large and it burst free from the wall. Several dozen of the small zenos raced inside, screeching and leaping at the soldiers. One leaped at Rob who flinched and shielded his face. Admiral Stark rolled his eyes and carelessly took aim, then shot the Zenos, which was sent flying back by the momentum of the bullet hitting it. It shook itself and screeched at him, but as he shot another bullet it fell silent, blood oozing from its body.
Four of the twenty men that had been in the room were dead, and one was wounded. Yet still more Zenos came. Admiral Stark took aim and fired, hitting one of the creatures in the mouth and striking it dead. "Bullseye." he muttered, then turned to point his gun at another zenos. He'd been keeping track, and so far fifteen zenos had died by his hand. Yet there were at least that many currently in the room right now, and more kept coming. "Retreat!" Admiral Stark called, and the soldiers, still firing at the zenos, backed away. They all entered the room and Admiral Stark closed the door, bolting it before turning to them. "That won't keep them for long, so I've set land mines underneath the ground in this room. They'll activate when the button on the far side of the room is pressed."
They all ran over to the door at the other end of the room, and hid behind several large chunks of concrete that Admiral Stark had put there after the Zenos Flash Tower had crashed, to use as cover. Admiral Stark pressed the button and a beeping sound filled the room, then the zenos burst through the door before they'd all had time to reload their guns. "Shit!" one of the soldiers shouted. Suddenly the ground exploded beneath a zenos' feet, and it made a loud whining sound before falling to the side with its legs in the air like a spider. As the zenos progressed across the room, running over their dead kin only to be killed as well by land mines, the soldiers fired into their midst and killed more than the land mines did. However, not all of them were dead when the last of the land mines had detonated. Admiral Stark shot one final zenos, then his heart skipped a beat as a large zenos with huge spikes sprouting from the back of its head stepped into the room. He'd remembered that Verakka had called it a zenos poison drone.
"Get back!" Admiral Stark shouted as he removed a panel in the floor and brought out a bazooka. He aimed it at the ceiling over the Zenos's head, then fired. The ceiling exploded as the missile hit it and the Zenos screeched in pain, falling to the ground as ten tons of concrete fell on it. Admiral Stark threw the bazooka aside and retrieved his handgun as Rob shot one of the small zenos that were crawling over the wreckage. They all emerged into the courtyard and bolted the door, then one of the men crawled into an AV and aimed the gun at the door. As it burst open he opened fire, pelting the zenos with bullets. At the end of the courtyard another door opened and five men burst out, followed by several of the zenos. "Sir! We're under att--" before he could finish one of the zenos leaped on him and bit into his neck, killing him instantly. The other four men shot furiously at the zenos and shut the door again, locking it before running towards Stark. "Where are all the other men?!" Admiral Stark demanded. "Fifty dead, twelve wounded, the rest got into three of our helicopters and flew off. They landed on top of a building and are shooting at the zenos from their new vantage point with sniper rifles." the first soldier replied. Fifty?! Stark thought. "How--" before he could finish three Zenos Poison Drones burst through the door the soldiers had just come from, and the man in the AV turned his fire on them. He felled the first one, and knocked the second one unconscious, but the third one bit the soldier and flung him high into the air before swallowing him.
Admiral Stark turned and shot the Zenos Poison Drone in the eye, blinding it, and it screeched before ramming into a wall and dying. "Gods damn it all, we need assistance!" Admiral Stark shouted, once again turning his fire on the many zenos flooding through the doors. He yelled as one of them shot fire from its back, killing a soldier. "What in the hell are these things?!" he yelled.