A scent carried on the breeze. The scent was acrid, rank with the oil and fire of guns. It stirred the night air, awakening old memories. #23 raised its head to the sky. It knew it was #23. #23 remembered the flash of gunfire. It questioned neither of these facts, giving its voice to a howl. Slowly lifeforms tore themselves from the landscape, a chorus of screeches and growls accompanying their rise.
#23 gave them a cursory inspection. The death slumber fell away gradually and their movements blended until the innumerable beasts were one horde. #23 felt some satisfaction, wings unfolding. It took off and swooped over its fellows. Time to feed.
It began with a green glow. #23 hovered nearby, older things staring through its eyes. #23 sensed their reservations and as the glow strengthened felt confusion blossom in the horde below. Great lumbering beasts wheeled about, smaller skittering predators fleeing for cover. The glow coalesced, becoming metal darker than night. Machines, encrusted with ancient morass plodded forward. The urge to strike flooded #23's mind but something held it back. It hung in midair and watched.
The metal demons strode toward the pensive horde, then walked right past them. Great floating pyramids phased into existence, bathing the tyranids in green light. #23 caught the scent again and screamed into the night. The horde wavered then flowed after the mechanical monsters. They would feed together.
Cold dawn lapped the world. Light trickled into the sky slowly, forming veins of burning red against the wretched night. #23 flew through it, searching for prey. It found it soon enough. Bright beams punctured the night. #23 knew they sought it and twisted in the air, bringing its weapon to bear. With a thought a lance of diamond carapace spat from the gun, glancing off the bright yellow of a floating tank. It did little but scratch the paintwork and the vehicle roared to life, zooming away. #23 gave chase, its brothers flitting alongside.
The beams came again, this time finding a target. #23 felt a wingmate falter, spiralling to the ground. It crashed into a hill, leaving only ichor and dead flesh.
The sun crested the horizon suddenly and lit up a battlefield. The horde flowed towards a great tower, the machine warriors stalking alongside. Their floating pyramids still glowed hellishly, unleashing sparks that made #23 tremble. Arrayed against them were a motley assembly of tanks and soldiers. In the midst of it all burned a great and terrible figure, hand dripping with blood. #23 plunged into the fight without fear.
#23 fired again and again at the tanks, its lances scattering off their armoured hides. It felt a great frustration with its failure. The tanks scored hit after hit upon its brethren, thinning their numbers dangerously. Turning in the air it descended, opening its claws and charging a one. Bullets whizzed past its nose but it stayed the course. Its claws scored deep marks in the tank, tearing it apart. #23 perched atop it, tearing out the soft, squishy things inside and devouring them. Its surviving brother had followed and torn apart another vehicle. It too was embroiled in ingesting the occupants.
The screams of the dying were sweet to #23 but they were cut short. The great pyramids of the metal demons unleashed swathes of energy, clearing away ranks of enemy warriors. #23 noticed another vehicle that had escaped the blasts and swooped, overturning it. It tore this one apart too.
When it looked up the tower was right in front of it. Lines of ancient machines hung from its windows, they churned and crunched in inscrutable industry. #23 was fascinated, both by their workings and the fierceness with which they were defended. It made to pluck one from a window when a roar sounded that made it start with fright. Around the tower strode a burning figure. Its veins were lined with lava and it held a great blade aloft.
#23 tried to back away. The voice in its head sensed its fear. A massive snake beast of the horde leapt at the fiery man. The blade came down and the snake beast lay decapitated. The fiery man raised a bloody fist to #23.
#23 leapt at the building, hooking onto the rocky wall it climbed the side, away from the bloody hand. More explosions rang in its ears, coupled with the roars of the fiery man. #23 left them far behind, cresting the tower. Little beings scurried about, yelling and toting little guns. #23 aimed its gun and a blast cleared them away. Some leapt from the tower as the venom burned away their flesh.
One in particular interested #23. It went over the side after him. At the bottom the little man yelled some more. #23 loosed spores and spying another tank it flew after that instead. The spores fell to the earth, splashing the man with toxins and chewing away what little life he had left. #23 missed his screams, absorbed with new prey.
When #23 finally finished its hunt it realised it had lost something. The voice that had once guided it, the hand that had driven it was gone. The metal demons had vanished too. Their great pyramids faded as ephemerally as they had come. It felt free and hungry. The tower was no longer interesting. #23 flew until it found a brother and together they went in search of prey.
(Based on Necrons/Tyranids vs. Eldar/Marines. Final result a draw with no troops left on either side to claim objectives. Eldar/Marines claimed victory based on points)