
The guild can't identify some of their potions. They send them your way. Your job is to discover what effect they have and label them correctly. Learn the reactions the potions have with other substances, in the furnace or... your own body?
Each potion reacts differently when exposed to heat or other materials. Watch carefully. The reactions will tell you what the potion actually does.
Figure it out, write the correct label and send it back to the Guild.
Saves everyone time. Of course, if the potion melts your bones or turns your vision inside out, that's not my problem. And definitely not the Guild's.
Nobody should be wandering down here. If they are, they are weirdos, and they probably have weird requests. I hate weirdos.
The Guild says you work for them, which means they keep an eye on your work. They will help you out so you don't do a sloppy job, whether you like it or not.