Illusions are rarely encountered. Psychic enemies are already scarce, let alone those capable of creating illusions.
Although Han Rui and the others had encountered illusions in the past, that was a long time ago and they lacked much experience in dealing with them, so when Wang Tao said they had been ensnared, everyone but Yang Changhong panicked.
Fortunately, Wang Tao had experience dealing with illusions. Although he could not see through this one, it was enough to recognize it as an illusion.
Typically, the user of an illusion would isolate each victim to break them down one by one, which is the most energy-efficient method.
The method of separation likely involved using illusions to disorient them, leading them to stray from each other until they realized that their teammates had disappeared, leaving them alone.
Of course, besides separating them, the illusion might also deceive their vision, make them see teammates as enemies, causing them to attack each other.