Skraal took a deep breath and watched everything unfold.
The Corpse Body Kings cast different kinds of ghost magic and death magic, using their increased power to also control the dead Black Ants against the horde of Black Ants to stop them on the track.
The effect of emotional warfare is nothing much as it can be expected that black ants have no reason to be scared as they cannot be afraid of anything. They just deemed the dead black ants attacking them as enemies and confronted them.
They do not have relatives; they do not have any kind of connection with each other. A single mind controlling more than 100,000 minds is the explanation.
Hive Mind is something like this. It is an important force to be reckoned with.
But as the battle went on, Skraal knew that ten corpse-kings would not be able to take out all the enemies. Skraal himself could use magical spells as much as he wanted.