The water will serve as the base of the curative salve I'll make for the deer. For curative properties, I need some earthroot. Herbalists know how to find it, so if we're unlucky and you aren't one then you'll need to find one to help us out.
Finally for potency, I need some lunar fungus. Finding lunar fungal blooms is easy enough; they're all over the place in caves just to the east of here. Moonkin reside in the caves and they're irritable as of late, so be careful.