After seriously hours of searching... Gobblah was finally pointed in the right direction. Hoping to avoid what might be seen as a spoiler, I'll try to keep it brief.

Mechanics wise... are the bottles of water you can buy from the druids near the glowy green mushrooms able to be used to make potions?

Being incredibly poor at the moment, I can't afford to spend 10gp and it turn out to be in vain. :3

FOIG!

Thanks, Blubie. >.> But this has nothing to do with setting or anything. This is a mechanics question. I mean, my character is standing over the bottle before purchasing it, able to tell if he can put "magic stew" in it or not.

I'd like to take this time to suggest that we ban FOIG because it's annoying like a masseuse with Parkinson's.

In the tunnels behind old Goblin Town, the group of gnolls have some magic potions for brewing. Try those until you know for sure about the ones in Mycopolis.

Heh. Tried getting to goblin town but kept getting butchered by the uber rats that infest the sewers. And now Gobblah's remains rest at the bottom of the canal. =P

Oh well. I can make another goblin shaman. *Wanders off to think of a concept.*

The gnolls are in the tunnel behind the ruins of Goblin Town. It used to be haunted, but I'm pretty sure there aren't any spawns in there anymore!

The sewers are on the completely other side of Lower.

If a bottle is usable, it's already got a purpose. If a bottle does not have magic properties, and is a magic potion bottle (base item), then it can be used for crafting.

When you guys were talking about "Goblin Town," I thought you meant Sewer Town!

D'oh!

and another goblin dies of ignorance - no wonder they breed so fast!