Main mission - Enter the Mournweald | Act 1 Dungeon Siege III Guide

After leaving Chapterhouse you will reach East Forest (M9) - while you're there, it's worth to finish A Loss for Words and Hiding Out. Your main mission will be reaching the tree found in Mournweald - in order to reach it, you will have to fight your way through a horde of spiders and wolves in the West Forest (M9) and fishmen inside Mournweald itself (M10).

The battlefield is one of the key locations in the game.

After getting there you will talk with the Radiant Youth (M10,1) who will teleport you to the edge of the forest. Return to Odo and show him the Montbaron Signet which you've found by the corpse (M10,1). He will tell you to open the portal (The Battle for Raven's Rill).

M9 - East Forest

M10 - Mournweald