Inside the Heaven Refining Cauldron, Wu Qi and Princess Zhang Le's bodies were joined as one. Led by the former, they were making a breakthrough for the realm of Dao Breaking.
If it were Wu Qi alone, he would have long made the breakthrough. But, he had to bring the princess together, and that required him to pour in a hundred times more effort. Fortunately, the princess was cultivating the Primordial Dao of Divinity. Unlike the immortals and buddhas, she did not have to face any bottlenecks. So long as she possessed a sufficient aptitude and accumulated enough energy, the breakthrough would come naturally to her. If it were another female immortal, it would not be so easy for Wu Qi to help her break through the realm of Dao Breaking, even if he were willing to spend all of his blood essence.