Zhao Hai had always thought that the curse spell was the most troublesome spell because it was one of the few spells that could be used directly on the soul. It was so powerful that it was impossible to guard against it.
For example, if Zhao Hai and the others had been hit by some other spell instead of a curse, Zhao Hai would have noticed it immediately. However, because they had been hit by a curse, Zhao Hai did not notice it, which was why they had been ambushed by grimace twice.
It could be said that the curse on Zhao Hai and the others was not troublesome. It was a very low-level curse, but because of its special use, it was very difficult to detect. Zhao Hai was not afraid of this curse. What he was afraid of was that someone would use it.
Zhao Hai had passed through many worlds, but there weren't many that had curse Arts. Zhao Hai had only seen one before, but for a curse art to appear in the five spirit world was out of his expectations.