Reidoth

Reidoth is an old, male, human druid who lives alone on the outskirts of Phandalin. He is known to travel frequently throughout the Lakelands Region, sometimes leaving for multiple months at a time. He is an idiosyncratic man who cares mostly for the woods and natural things.
The adventurers first learned about the old sage from Qelline Alderleaf, one of Reidoth's few friends. They sought him out in the village of Thundertree, and after finding him, were abruptly welcomed into his dwelling place. The druid seemed to be mostly friendly, if not a little incautious. When asked about the location of Cragmaw Castle, he offered an exchange of information for a favor: the elimination of a young green dragon in the area. The white-bearded guru admitted to the adventurers that he was in Thundertree researching the strong planar signatures that flowed through magical tethers in the area. The dragon was an unwelcome obstacle, as were the cultists who worshipped it.
The party accomplished all that Reidoth asked, discovering a few things about him in the process: he had some control over the natural elements, he liked to transfigure into a squirrel, and he was easily distractible. After the exchange of information, Reidoth wished the adventurers well on their way, remaining in Thundertree to continue his studies.