I define illusionist a man that don't uses his mind and body to create strategies and plans that come within us, like Zhuge. He just studies the wind (Chi Bi battle), the nature and other aspects to win the battle. A illusionist, on the other way, have many means. A jerk( we think of it too), the one that don't cares about the whole situation, but on winning, no mattering how many people die(i think Sima Yi is like this one),in the worst situation, the one that lies and even emplots someone better than him to give him advices and they say to the commander ( i'm not saying this happens). Well, a illusion can also be higher than strategy, like Muirghiel said.An illusion that is only called illusion if someone have good strategies.
Zhuge Liang was a illusionist, i can say. But the illusionist that surpasses the strategy.
-Sleeping Dragon: always prepared, cautious and clever, hard working... a brilliant strategist.-