Randolph who managed to break through the defense of the bone wall directly landed a punch on the Necromaster's face. As the monster realized what had happened to him and tried to get back up, Randolph showered him with a barrage of attacks.
The successive attacks were deliberately done by Randolph. Not only to make the Necromaster unable to cast the skill that had been penetrated by Randolph but also to make himself weaker.
Randolph knew that the monster had no soul but still needed a core for its life, To get the core Randolph had to destroy his body one by one. Randolph couldn't guess where the core was.
Randolph's first target was the head of the Necromaster. After Randolph threw a fist that hit the Necromaster's temple causing his skull to crack, there was a core inside the head.