I've started the AoW a few weeks ago, and our group is loving. I have to say the team at Paizo is doing a great job.
The group has been very creative with the encounters. I'll give you a brief over view so you can understand what has happened with the water elemental and mold.
The group consists of:
Brother Gabriel, Paladin of Heironeous
Dak (Human Slang for a long winded elven name), Transmuter
Van-ro, elvish druid of the Bronzewood Lodge
and Marq, a goblin wannbe assasin (specializing in Orcs), under the care of Brother Gabriel
The story behind the brown mold is easy. I allow creative manipulation of spells in my campaign with a succesful spellcraft checks. Dak was abble to shape Tensor's floating disk to have an edge and spout. This allowed him to scoop up the Brown mold in the Cairn and place it within a metal container.
They are now using it to cool their cold storage section of their new basement within the old manager's offive. Marq has been busy burrowing new chambers for the group on his off time, and one of these has be come thier freezer.
Can Brown Mold be stored in Metal Containers, and for how long?
And they've been throwing in bread every so ofter, do you think it's enough to sustain the mold?
As for the Water Elemental. When they encountered it, they were succesful at defeating it. But unknown to them, the creature had been reduced to 0 hps and was disapated within the water. Brother Gabriel was able to detect the undead future within the complex, so the group decided to pump out the chamber before going into combat.
After some very lucky rolls, they were able to acquire a foot action, mine pump from Dak's employer, Ellival Moonmeadow. They also aquired a large amout of piping and paided a pretty penny.
And so they sucked out the water, draining the room over the course of a day or so, to the point where the ghoul attacked them.
During the time they were pumping, the elemental regained concesious and was sucked through the tube. The Paladin detected it at the last second. The Druid was the only one that had a chance at stopping it, but a poor roll let it slip by.
Here's the kicker, in my campaign, the cairn is only a short walk from town, 10 or so minutes, its also fairly close to the house. The PC's aquired enough tubing to run the hose from the cairn to thier garben at the mine manager's office. They wanted to jump start Dak's herb garden.
The garden is now permeated with the essence of the evil water elemental.
Weeds continously grow, about a foot a day. What would yousuggest would be the means for them to remove it? The more complex or interesting, the better.