While dual cultivating, he opened up her meridians and chakra points, ensuring her yin constitution would be able to be used to its fullest potential. 

Finally, after several weeks of training and dual cultivating, they both reached their limits. 

They were dual cultivating in the middle of the forest, when both of them started orgasming together. 

This orgasm was more intense than normal and Quan Yu's cum was literally pouring out of her tight pussy which was concurrently filled with his cock.  

"Qu..Quan..Quan Yu... what...oooh oooh  oooh" Rhuu Yen moaned as her arms that were wrapped around his head opened wide as her face looked to the sky. 

Quan Yu, who was hugging her in return simultaneously opened his arms too and also faced the sky as the huge storm that was building up around them suddenly poured with a torrential rainfall.

The sky cracked as a huge bolt of lightning shot downwards at them. 

Quan Yu has heard of the Heavenly Tribulation, where the heavens would punish when one graduates from the Houtian stage to the Xiantian stage, or from one Xiantian level to another.

Many Houtians perish in this process, but yet a good number of masters succeed too, through a tough and agonizing lightning ordeal that would take months to recover from.

Strangely, Quan Yu never experienced this when he jumped from a low level houtian to a low level Xiantian. Perhaps the heavens took mercy on him as he was blinded, was heavily injured and was a eunuch at that time.

Quan Yu instantly drew a sword from his storage ring and slashed at the lightning bolt. 

*BOOM*

He managed to deflect the lightning, but the sword was in ruins, half melted and bent. 

Another, bolt of lightning flashed and again Quan Yu withdrew another sword and deflected it. 

"This isn't good. I only have another 3 swords in my ring" he thought as he threw away the second destroyed sword. 

His hand was numb from blocking the lightning bolt, and he didn't know if he could continue doing so.

As he watched the next lightning bolt form and strike at them, he couldn't withdrew another sword in time.

Both of them screamed as the lightning struck them.

However, as they were entwined together in their dual cultivation circuit, rather than fry their meridians, organs and flesh, the lightning instead travelled through their meridian loop.

Quan Yu with his enlarged meridians and Rhuu Yen with her Yin constitution managed to hold on, but lightning shot out of all their orifices.

Their eyes, nose and mouth shot lightning back at the skies, while their eyes shot lightning at either side, causing the nearby trees to catch fire.

Their asses shot lightning harmlessly into the ground

However, Quan Yu's penis shot lightning at Rhuu Yen's pussy and her pussy in turn shot lightning back into his penis, making them both scream in agony.

Their flesh melted together, making them truly one body.

While Quan Yu's brain was being fried with electricity, his mind suddenly had an inspiration from the martial arts scroll he read in the cave.

The Sword God Zhang Meng's ultimate art was called "Cut" and his final inspiration and technique was called Cut

Another lightning bolt flashed at the conjoined couple when Quan Yu drew a third sword

"Cut" he whispered as he used his sword to cut at the sky

There was no wind, nor any sound as the sword silently cut at the sky.

However, this time the lightning bolt was cut in half and disappeared!

"Cut" Quan Yu said again and this time, the dark clouds were cut in half

"Cut.. cut...cut" he said, cutting the clouds into many pieces, scattering the Tribulation clouds to nothingness.

Both of them breathed a sigh of relief at overcoming the tribulation.

Quan Yu wondered how the bandit boss and his underlings overcame their tribulation as there was no way they would have survived this.

Perhaps their method of stealing other's cultivation allowed them to bypass this ordeal

What Quan Yu didn't know is that this tribulation was much more intense as not only were they both going through tribulation together for their next level, the heavens decided that Quan Yu, who was spared a tribulation because it pitied him were now doubly envious of him due to his fast progress. Furthermore, people with special constitutions like Rhuu Yen normally more intense tribulations

Rhuu Yen moaned as pain wrecked her whole body, and her flesh in her pussy was completely burned.

Both their bodies were blackened and their hair were burnt and frazzled

Suddenly, they both groaned as their dantians started cracking.

"Aaagh" Rhuu Yen screamed as her dantian broke. Quan Yen suffered his dantian breaking silently as Rhuu Yen smothered his face in her breasts as she hugged him tightly.

Hours later, Quan Yu opened his eyes. Rhuu Yen was still on top of him and he felt his cock still inside her.

But both of them were charcoal black and if the wasn't breathing, he would have thought she was dead

"Rhuu Yen?" he said, slowly shaking her

"Mmmmm... Master?" she groaned as she opened her eyes

"Yes, we made it. Congratulations" Quan Yu smiled

Although both their dantians were empty and they were now powerless again, he could sense that she had jumped Peak Houtian stage and was now an Early Xiantian! He himself was a Mid Level Xiantian.

"I...I'm a Xiantian?" she gasped and happily kissed him. There was no way she would progress this fast if she was still in her old sect.

"Yes... but lets get washed up.." Quan Yu said as the smelled their body odor.

Not only had their bodies expelled their impurities, they smelled of burnt flesh.

As she got up and separated from him, she groaned as not only were there their joint melted flesh in her, but she had a regenerated hymen which she tore again, evidenced by fresh blood.

The area around the was completely devastated from the lightning strike and fire.

Fortunately they were camping near a lake, so it wasn't far for them to wash themselves off.

As they washed themselves off, all the impurities and burnt flesh sloshed off their bodies.

Even the burnt hair dropped off revealing silky smooth new long hair underneath.

As Rhuu Yen cleaned Quan Yu's back, he pointed at the other side of the lake

Normally, he could walk on water or fly. But now, his dantian was new and empty, so he couldn't do so.

"Hey, lets swim over there" he said as the other side looked quite pleasant, compared to the devastated area they were at.

Everything they owned was in his storage ring anyway.

"Race you there" Rhuu Yen said as she started swimming first

Quan Yu laughed and started swimming after her.