Xuan Yue, Chi Ling.
These two were the Demi Immortals that Gu Wen had the most contact with, and they also shattered his rose-tinted glasses regarding great powers among immortals.
The so-called transcendence above the mundane is but a fallacy; from the perspective of mortals, one who need not hustle for a living and can absorb the essence of wind and dew to live forever might be considered transcendent.
From the perspective of a cultivator, a True Monarch who can fly and escape through the earth with boundless mana could be recognized as a great power.
Going further up, the True Monarchs perceive the Venerables of the Dao Realm, who govern a continent and can command thousands of cultivators with irrefutable authority, as great powers.
The Venerables of the Dao Realm long for the hundred-thousand-year lifespan of a Demi Immortal, yearning to break free from lifespan restrictions, to roam the Void and live freely.