The technique required great precision; an error involving even a small amount of Qi could cause the illusion to disappear completely, leaving the user exposed.
For cultivators in the early realms, however, it was a fairly useful technique, a tool that could create openings at critical moments.
If someone could make an enemy believe that there was a person behind them, for example, it could create an opening large enough to attack.
It could also make a corridor appear longer, disorienting the perception of distance. An object could appear to be several meters away from its actual position, or the enemy could be led to believe that they were hearing footsteps that never existed.
However, there was a major problem: the more powerful the cultivator, the sharper their senses became.
After the Spiritual Awakening Realm, when spiritual sense was awakened, techniques of this level began to lose much of their effectiveness.
