Treant

From publisher blurb: Shepherd the Woodlands! With the Treant, a 10-level class for Labyrinth Lord (and other old-school fantasy role-playing games), you'll be ready to march to war in defense of the forest! With magic drawn from the forest, an uncanny ability to disappear in the verdant realms of the world and your terrible fury in battle the Treant is the great defender of the wild places in the world!