Instinct was a very scary thing, especially the attacking instinct. The attacking instinct of a beast was much stronger than that of a human. Instinct was not wisdom, but sometimes, instinct was even more terrifying than wisdom.
Just like a swordsman, he didn't practice anything else but drawing his sword. When he practiced this move instinctively, very few people could block it. This was the most terrifying part of instinct.
Demons were a kind of demon beast without wisdom and only had instincts. They couldn't become demons without wisdom, but they had very strong fighting instincts. It was because of this that many cultivators would rather face demon beasts and cultivators than these demons.
It was also because those spiritual monsters only had instincts but no intelligence that they would not be subdued. You either had to kill them, or be killed by them, or they would run away, or you would run away. It was impossible to subdue them.
