Three words came to mind:
Black Lip Leaves.
A rare and legendary poisonous leaf found only in a few cave environments that were damp and had been walked by demon races who had poison for blood, these leaves were so-named for two reasons:
One, they were as dark as ink. If one looked at them, not a single vein would be visible on a Black Lip Leaf; they were so dark that they absorbed all light and appeared nearly as shadows! Velvety and soft, they were both terrifying and pleasing to look upon.
Two, they could kill a person within one minute. Once the poison made its way into the bloodstream, it would turn even the strongest cultivator's blood black, causing them to spit up a sticky black substance before crumpling over, dead on the spot!
This tea had been brewed by a true expert. If it wasn't for the fact that Qiu Yunru had an exceptionally good sense of taste and had studied the alchemy of Spring Blossoms, Autumn Fruits for so many hours on end, he never would have tasted the slight tang of licorice and felt the tingling in his ears that was the signature first symptom of Black Lip Leaf Poisoning!
Even though he hadn't yet swallowed, his ears were already beginning to ring.
"Don't drink it," He croaked to Li Chenyuan.
"I wasn't going to," Li Chenyuan muttered. "Didn't I say that earlier?"
However, seeing the paleness of Qiu Yunru's face, his irritation evaporated, and he sprang to his feet.
"Qiu-ge--what's wrong?!"
Qiu Yunru doubled over. The ceramic cup fell from his hand, rolling off under the dresser as he braced his hands on the ground, feeling acid bubble up his throat.
"Black...Lip...Leaf..." He choked. It felt as though his throat was being boiled alive! All over, he was suddenly hot and sweating, as though his very blood was simmering over a fire!
The only antidote to Black Lip Leaf poison...
Was to drink the blood of that demon race with poisonous blood!
Meaning, he had no hope of survival!
That demon race was known as the Suan Demon race by mortals, named after the sour smell they carried due to the poison flowing in their veins. Next to Scholar Demons, they weren't considered all that powerful. However, due to the nature of their poison blood, even though they couldn't harness demonic qi well, they were renowned fighters, able to use their own bodies to poison enemies.
This sort of demon could only be found in the Demon Realm, or in the deepest and darkest of caves with the most ancient passages.
So, not anywhere that could be reached in thirty seconds!
Something hot and thick bubbled up Qiu Yunru's throat, and he gagged. Black blood spilled from between his lips and onto the floor, splattering and oozing like ink.
How many seconds had passed?
Too many. Qiu Yunru's mind swam.
Wasn't this incredibly unfair...? It was difficult to think, but he still felt a faint sense of injustice. After dying by slipping on the stairs, working for years to achieve immortality just for a life of peace, and training his body and mind to exhaustion...
Someone just had to come along and poison him to death?
What had he even done? Was he simply the unfortunate victim of a crazed killer? Had he offended the innkeeper so deeply in a way he hadn't noticed last night that he'd come up to poison both of them...?
How unfair...
A blue notification box appeared in front of him. His vision had gone mostly dark, so it was a bit blinding. It glitched at the corners wildly.
WARNING: Player Health Level reaching Death Zone. Exchange Demon Realm Reputation Points for HP?
Qiu Yunru tried to consider this for a moment, but his mind was like a slush of dirty snow being run over a thousand times by car tires until it became water. That is to say, his thoughts flowed to weakly he could barely think at all!
He clicked on the YES button weakly.
If he was dead, he couldn't exactly weigh the pros and cons of losing Demon Realm Points, could he?
Understood. Exchanging Points.
A sudden coolness washed over his body. Slowly, the darkness cleared from his vision, and he could once again taste the sour iron of the blood on his tongue. His ears were still ringing with a high-pitched noise, but he was alive.
Somehow, he had fallen onto his back on the ground without noticing. It was really easy to fall over without realizing it when dying, wasn't it? Shaking him violently with tears streaming down his face, was Li Chenyuan.
Qiu Yunru blinked up at him.
This kid had cried so much in just a few seconds that his nose was running, his hair had become disheveled, and his face shone like a river with tears!
Don't cry, Qiu Yunru wanted to say. I'm alive...Shouldn't it be me crying?...Holy shit, I almost died!
Just as with the Spirit Disintegrating Pollen incident, however, he found that he didn't even have the strength to open his mouth. He could only cough a little, spurting more black blood into the air.
Seeing his eyes open, Li Chenyuan frantically began to wipe at his face with his sleeves. However, it was hopeless. The tears wouldn't stop flowing, so as he wiped, he only made his entire face wet with his sobbing, looking like a maiden weeping over the body of her beloved at a funeral procession!
"Qiu-ge...?" He croaked, leaning down and pressing a hand to his neck to check his pulse. Every word shook. "Can you hear me...?"
Qiu Yunru managed to nod a little. He couldn't help but make a disgusted face.
This Black Lip Leaf poison really did make one's mouth taste absolutely awful!