The Hundred Clouds are the ultimate goal of the orthodox Dharmas. It means a shedding of one's karmic damnation and rejoining into the cycle of reincarnation.
"The Hundred Clouds" is a metaphorical term for ultimate peace, the transcendent state in which even the duties of Heaven are set aside. The Clouds are not power, although lesser Kuei-jin might see them that way; they are not illusions, though they might seem so to individuals who cannot understand them. By joining The Hundred Clouds (which the wise understand to be a symbol, not a group), a Kuei-jin reaches the peak of its being, even higher than a bodhisattva. Most leave this world behind after reaching such heights, vanishing to an unknown destination. Others chose to remain and guide others as bodhisattvas.