There was an extra ability that Kush's staff allowed him to do, that he could travel through the ground as long as it was made from earth. This was how he was able to move through the battlefield and continuously change direction.
He couldn't just stay underground though, as there was a slight catch. He needed to hold his breath to use the ability. Going through the ground was similar to going underwater. He could somewhat see but not clearly, and there wasn't really anything underground anyway.
He was more so using the ability of the golems to guide him to where he needed to be. Then would pop up at the perfect place every time anyone got close to him.
Kush lifted his hand up and touched his left eye.
"That was a close one, I thought I was going to get hit again. I can't let them get close to me. I can't let those disgusting things even touch me!"