If the Swarm were fighting the daemons of Tzeentch or Slaanesh, the battle might have been slightly easier to manage in some respects.
Tzeentchian daemons possess formidable Warp sorcery, which acts as a natural counter to the Swarm's massive numbers; even Ultralisks and Monarchs face a gruesome end if tossed into a Warp rift.
But Khorne?
The Blood God's forces possessed raw stats but lacked any semblance of strategy.
"I can hold the line a while longer."
The problem was the sheer volume. When a commander treats Bloodthirsters like expendable fodder, it becomes a tide that almost any force would struggle to withstand.
In a short span, the Overmind had already slaughtered over a thousand Bloodthirsters. To any Warhammer fan, such a feat would be seen as a humiliating blow to Khorne's pride, yet the Greater Daemons continued to surge from the portal without end.
Khorne's losses were catastrophic. Due to the presence of Vipers and Defilers, the battlefield was choked with toxic clouds and Blinding Mists. Every few moments, a Viper would lunge forward to snatch away a Bloodthirster or a Daemon Engine.
Even a daemon would hesitate at the sight: a thick, fleshy tentacle darting out from an impenetrable fog to drag a comrade into the darkness to be torn apart.
"Ah!"
The Tech-Priests of the Dark Mechanicum were nearing a breaking point as they watched their Chaos Titans being plucked away one by one.
"Stop pulling them! Stop pulling them! We have almost none left!"
If the battle continued at this rate of attrition, Khorne risked losing every Chaos Titan collected between the 30th and 40th millenniums. No matter how powerful their long-range batteries or how resilient their Void Shields, they had no defense against the Viper's Abduct followed by the Ultralisk's Kaiser Blades. It was a simple sequence: hook, gore, and end of battle.
However, the Ultralisk herds were also suffering. Only the Ultralisks could tank the frontal assault of Bloodthirsters, so their casualties were inevitably high.
The Overmind felt a pang of regret at the loss.
While he still had many Ultralisk herds in reserve, the narrow underground terrain made it impossible to maintain a low casualty rate. He estimated that over half of the Ultralisks he had just spawned would be lost. Of course, as long as the planet could be pulled out of the Warp, the Creep could reclaim the biomass from the carcasses, making the net loss acceptable.
"Seventeen!"
The Queen of Blades had just slain her seventeenth Bloodthirster, but fatigue was setting in. She panted heavily, her breath coming in ragged gasps.
Bloodthirsters continued to encircle her. In the distance, Daemon Engines spat hellfire shells capable of obliterating armored vehicles, but the Queen of Blades merely raised a hand, dispersing the incoming fire with a psionic shockwave.
"This is... never-ending!"
Such is the nature of daemons.
As long as the Chaos Gods desire it, the number of daemons can exceed even the Swarm. This is where the StarCraft universe is at a disadvantage compared to the Warhammer universe. The Zerg possess the largest and fastest-growing population in their own galaxy, but scaling up to the level of the Warp's infinite tides is an exponentially difficult task.
The tactical advantage the Overmind had gained through micro-management was slowly eroding under the enemy's numerical superiority. Yet, the Overmind remained calm. He knew his goal wasn't to exterminate every daemon in existence.
"I've won, Khorne."
On the surface of the Crone World, the wormhole was now close enough to touch.
"This was only our first skirmish. Next time, you should probably bring the other three Gods along to help you."
The moment the planet touched the wormhole, the entire planet accelerated into the rift. In a matter of seconds, the world vanished from the Eye of Terror.
On the other side of the wormhole, the planet emerged into realspace.
The Overmind had won.
Victory does not always require the total annihilation of the enemy; as long as his objectives were met, the Overmind considered it a win.
The Bloodthirsters remaining on the surface felt their Warp-given strength vanish. Their physical forms shrank as the Warp energy dissipated. The towering bodies that had stood taller than Ultralisks shriveled to half their original height within a few breaths.
Looking up at the towering Ultralisks raising their forelimbs, casting massive shadows over them, the Bloodthirsters could only sigh.
"Oh, bad luck."
THOOM!
An Ultralisk's massive foot slammed down, crushing the Bloodthirster beneath it and sending a spray of ichor hundreds of meters across the ground.
The other Bloodthirsters shared a similar fate, flattened by the weight of the Zerg advance. Some Daemon Engines tried to flee, but they were overturned by the charging herds. Only a few managed to retreat through the closing portals back into the Warp.
The Overmind had secured his victory.
"I can't truly kill those daemons, but it will likely take them quite a long time to reform after losing this many of their kin."
The next task was to clean up the battlefield.
The Overmind first reclaimed all usable biomass on the planet. The fallen Zerg were processed into nutrient-rich spawning pools and absorbed by the Leviathans' tentacles. In terms of biomass consumption, the Zerg process was remarkably similar to that of the Tyranids.
Biomass could not be wasted; many units had died in this struggle. The Swarm would soon have to face the main Tyranid hive fleets, and they needed to stockpile as much resource as possible. With sufficient resources and larvae, the Zerg's reproduction speed actually exceeded that of the Tyranids.
"Ah, one more thing. My daughter."
"I am here, Overmind." The Queen of Blades rose from her rest. "Your orders?"
"Notify the Eldar to claim their world. The Creep tumors will burst and dissipate once the biomass reclamation is complete. Tell them not to worry. As for any remaining daemons, they can handle that themselves."
The Overmind wasn't certain if small, hidden portals still existed on the planet. If a few minor Slaaneshi gates remained, he didn't want the Eldar blaming the Swarm for a messy job.
"Also, tell them to find what I want as quickly as possible. If they fail, I won't hesitate to turn my attention toward their Craftworlds."
"Yes, Overmind. I will convey your will."
Though the Queen of Blades was once an Eldar in this form, her loyalty to the Overmind was absolute. As long as the Overmind existed, the Swarm was unbreakable.
The battle scars on the Crone World were irrelevant. The planet had been ravaged by daemons for eons. Furthermore, the Eldar didn't actually need the planet itself; they sought the Spirit Stones—special minerals that could capture their souls upon death to prevent consumption by Slaanesh. For the Eldar, these were a necessity for survival.