This walking cyprus tree bears terrible scars where its bark was scored by acid. He lives in the large wooded area astride the most likely route to Vitriolic falls.
Whatever warmth or empathy this treeherd might have had was destroyed by his injuries and seeing fully two thirds of his treasures forests killed by acidic waters. He does not know that the destruction was artificial - the result of the acid-laden Anur river being diverted to allow for the construction of the Bronze Keep. If he found out, he would take all measures possible to destroy the keep, possibly enlisting the help of the nearby mountain Giant tribes.
This fellow is very similar to # 2 Haun the Burning in echomirage's most excellent 30 Treeman submission.