Chu Yunsheng had never killed so many people before. He didn't even know many of them exactly. But he still did not stop killing.
If he did not want to die, then he had to carry on killing, no matter how many of them, how familiar he was with them.
It was not that he did not want to order the swarm to attack them from outside. If he really did it, then the swarm would lose its advantages and he would lose the fight.
Moreover, Dark had just leveled up less than 3 days. Although its control range had increased, if it was outside the creep area, it would require a tremendous amount of Yuan Qi energy from him, and it would also be much more difficult for him to control the swarm.
It was exactly what happened when he tried to save Tan Ning. At that time, he almost lost control of the swarm.
Dark and the swarm was his last resort. If he ordered them to attack now, that meant he was lost already.