Controlling people?

The formations of the four sects collapsed more and more as they felt the strain of being attacked from the dark. It was as if whatever was attacking them wouldn't give up no matter how many times their attacks failed.

Though it didn't seem like they had a problem since the four sects weren't able to hurt their attackers.

They tried to fight back against the attackers, but they were never able to pinpoint the attackers.

No matter how they tried to fight back, they would always miss.

In a state of being constantly attacked from the dark like this, there was a certain amount of stress that was on them. They would have to be in a state of high alert this entire time that would wear on their minds.

In short, they were slowly going crazy being in this state.

It was similar to being trapped in a cage with a fly that kept annoying you. It would slowly wear down on you until you couldn't take it anymore.