Makes potions actually work

Each night he would take Mother Dobbs’s folk cure to those who were too timid or prudent to fetch, them for themselves. He would pick up the packages as the old woman retired for the evening and set out promptly on his rounds. Well, almost promptly. Of late he had taken to examining the potions himself, in his quarters in the attic of Mother Dobbs’s house, before starting to deliver them. At first he sought to understand the cures, but later, aided by his knowledge of how spells truly functioned, he began to try to improve upon them. Up till now no one had complained.

(...)

“Who in Mishra’s name are you ?” she snapped. “What do you think you’re doing ?”

“Doing?” said Jodah. The world still rocked around him, and it was the best reply he could manage.

“The potions, you idiot child,” said the young woman. “What do you think you’re doing with those potions ?”

Jodah blinked. “I just run deliveries. Don’t know anything about . . . ”

Then the young woman balled one hand into a fist (the one without the blue flame) and stomped her foot on the paving stones. “Don’t play the fool with me, child. We don’t have time for it.”

“I don’t know what you’re talking about,” managed Jodah, wondering if he could talk and call on his magical energies at the same time.

“Do you know what is in one of Mother Dobbs’s ‘potions’ ?” she said, her voice dripping with venom. Jodah flinched at the mention of the name, and she continued. “Yes, I know who you work for. I purchased one directly from the old woman a few days ago.”

Jodah shrugged, and she continued. “Mare’s milk, mineral oils, and the yolk of an egg. It could clear out your lower track, but that’s all. But do you know what the potions you deliver do?”

Jodah’s back stiffened, and a line of sweat dripped down his spine. He had been found out.

"There’s an odd difference between the potions the old woman sells and the ones that are delivered in the dead of night. The ones you happen to deliver really work. They clear the spotted plague, or whatever is afflicting the drinker!”

Jodah mentally cursed himself, but it had seemed so obvious to try and help Mother Dobbs’ potions with a little magic of his own. He had hoped to just make them drinkable. He had never thought the difference would be so incredible or so obvious.

***

The Gathering Dark, Chapter 3