Forest of Tears.
Aggressive mobs wander much of the area, many of which can detect hidden / invis. There is a nasty panther which resides in the few rooms to the southwest of the entrance to Tree of Life.
Two thirds of the area has the same room name, "The Misery of Mourning" (basically the whole left side). Generally a bad place to have to CR, so if you're in trouble be sure of where you are.
The only notable mob is Salix, wandering around somewhere.
Walk ( 7w ) to get from DH to the room marked in blue.