I am not sure which spell it is, and I am not sure if it even is a spell. I got the quest from my guildmaster when I hit 14, so I was hoping I would get a spell after all this running around.
Well, I found the well on top of the mountain. It's not a well, its a spring. Northwest of the Crossroads, there is a big mountain. The one you are looking for has a house full of orcs at the south end of the base. Go up, and get ready for a little bit o combat. There are level 10-12 mobs up there. After you retrive the sample, you get to find earthroot and kodo horns. I am a skinner/leatherworker and I don't know any herbalists. I am going to the auction house as soon as I get done here. I will post updates as soon as I complete the quest.